Hip replacement navigation systems and methods

ABSTRACT

Hip joint navigation systems and methods are provided. In some embodiments, the systems and methods described herein determine a table reference plane that approximates the Anterior Pelvic Plane. In some embodiments, the systems and methods described herein measure a pre-operative and post-operative point. In some embodiments, the comparison of the pre-operative and post-operative point corresponds to changes in leg length and joint offset. In some embodiments, the systems and methods described herein determine an Adjusted Plane. In some embodiments, the Adjusted Plane adjusts for tilt by rotating the Anterior Pelvic Plane about the inter-ASIS line. In some embodiments, the Adjusted Plane improves correlation between navigated cup angles and post-operative images.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication including U.S. provisional application No. 62/471,185, filedMar. 14, 2017 and U.S. provisional application No. 62/521,097, filedJun. 16, 2017, each are hereby incorporated by reference in its entiretyunder 37 CFR 1.57.

BACKGROUND Field

This application is directed to the field of hip replacement, andparticularly to surgical tools and methods for establishing a referenceplane. This application is also directed surgical tools and methods forcalculating leg length and joint offset.

Description of the Related Art

Hip replacement surgery is common and getting more common by the year.One persistent issue with hip replacement is poor placement of the cupand ball components of the prosthetic hip joint. For example, the cup isoptimally placed in a specific abduction and anteversion orientations.While an acceptable window of deviation from the optimal abduction andanteversion angles has been observed in clinical practice for severalreasons an unacceptably high percentage of patients have the cup of theartificial hip joint out of this window.

Unfortunately, misalignment can lead to dislocation of the hip as soonas within one year of the implantation procedure. This is particularlyproblematic because recovery from a hip procedure can take many months.Patients undergoing a revision so soon after the initial implantationwill certainly be dissatisfied with their care, being subject toaddition redundant surgery. Of course, all surgery carries some degreeof risk. These poor outcomes are unsatisfactory for patients andsurgeons and are inefficient for the healthcare system as a whole.

SUMMARY

There is a need for improved systems and methods for providing forproper alignment of hip components with a patient's anatomy during a hipreplacement procedure. This can involve use of a table reference frame.This can involve use of a vertical reference plane. This can involve useof a reference plane that approximates the Anterior Pelvic Plane. Thiscan involve providing the user with additional information related tothe anatomy including leg length and joint offset.

In some embodiments, a method of positioning a medical prosthesis isprovided. The method can include establishing a vertical plane with ameasuring device. The method can include positioning a probe to contacta point. The method can include recording a position of the probe whenthe probe is contacting the point before replacing a joint. The methodcan include recording a second position of the probe when the probe iscontacting the point after replacing the joint. In some embodiments, acomparison between the first position and the second position indicatesa change in leg length or joint offset.

In some embodiments, the method can include coupling the measuringdevice and the probe to a patient. In some embodiments, the point is astructure. In some embodiments, the point is a burr. In someembodiments, the point is an anatomical landmark. In some embodiments,the method can include determining cup angles relative to the verticalplane. In some embodiments, the method can include positioning a medicalprosthesis at an angle relative to the vertical plane. In someembodiments, the method can include manually repositioning the femurafter replacing the joint. In some embodiments, the method can includeestablishing a horizontal plane with a measuring device, wherein thevertical plane and the horizontal plane define a reference frame.

In some embodiments, a method of positioning a medical prosthesis isprovided. The method can include establishing a vertical plane with ameasuring device. The method can include projecting a pattern of lightonto the leg of a patient. The method can include recording theincidence of light on the leg of a patient. The method can includereplacing the joint by inserting a cup, wherein angles of the cup aremeasured relative to the vertical plane. The method can includeprojecting the pattern light onto the leg of the patient after replacingthe joint. The method can include repositioning the leg to align therecording of the incidence of light with the pattern of light.

In some embodiments, the method can include recording a position of aprobe when contacting a point pre-dislocation. In some embodiments, themethod can include recording a position of a probe when contacting apoint post-instrumentation. In some embodiments, the method can includedetermining a change in leg length. In some embodiments, the method caninclude determining a change in leg length in the vertical plane. Insome embodiments, the method can include determining a change in jointoffset. In some embodiments, the method can include determining a changein joint offset in a plane perpendicular to the vertical plane. In someembodiments, the method can include establishing a horizontal plane witha measuring device, wherein the vertical plane and the horizontal planedefine a reference frame. In some embodiments, the method can includerecording a point in the reference frame. In some embodiments, themethod can include recording a point pre-operatively in the referenceframe. In some embodiments, the method can include recording a pointpost-operatively in the reference frame.

In some embodiments, a surgical system for assisting a surgeon inobtaining correct orientation of an acetabular prosthetic socket in apatient's acetabulum in provided. In some embodiments, the instrumentcan include a support device. The instrument can include a firstelectronic orientation device having a coupler for releasably couplingthe first electronic orientation device to the support device. In someembodiments, the first electronic orientation device comprises at leastone inertial sensor. In some embodiments, the first electronicorientation device and the second electronic orientation device areadapted to establish a reference plane based upon a direction ofgravity.

In some embodiments, the system can include a probe assembly comprisinga base portion and an elongate member configured to pivot and translaterelative to the base portion, the probe assembly comprising an secondelectronic orientation device, wherein the second electronic orientationdevice comprises at least one inertial sensor. In some embodiments, thefirst electronic orientation device and the second electronicorientation device are adapted to record a point when the probe contactsa point. In some embodiments, the first electronic orientation deviceand the second electronic orientation device are adapted to record apoint when the probe contacts a point pre-operatively andpost-operatively. In some embodiments, the at least one inertial sensorof the first electronic orientation device or the at least one inertialsensor of the second electronic orientation device comprises anaccelerometer. In some embodiments, the reference plane comprises avertical plane. In some embodiments, the first electronic orientationdevice includes a display configured to provide an indication of thechange in angular position of the second electronic orientation devicerelative to the reference plane. In some embodiments, the system caninclude an optical component configured to project a pattern of light.

In some embodiments, a hip joint navigation system is provided. Thesystem can include a jig assembly. The system can include a firstinertial navigation device configured to be immovably coupled to the jigassembly. The system can include an optical component configured toproject a pattern of light, wherein incidence of the pattern of lightcan be record to assist the user in realigning the femur to apre-operative position. The system can include a second inertialnavigation device configured to determine the orientation of a probewhen the probe is moved to touch a point.

In some embodiments, the pattern of light is a cross-hair. In someembodiments, the pattern of light is two lines. In some embodiments, thepattern of light is three points.

There is a need for improved systems and methods for providing forproper alignment of hip components with a patient's anatomy during a hipreplacement procedure. This can involve use of the Anterior PelvicPlane. This can involve the use of a table plane. This can involve theuse of an Adjusted Plane. This can involve providing the user withadditional information related to the anatomy including pelvic tilt androtation.

In some embodiments, a method of positioning a medical prosthesis isprovided. The method can include coupling a measuring device and probeto a patient. The method can include positioning the probe to contact afirst point. The method can include recording the position of the probewhen the probe is contacting the first point. The method can includepositioning the probe to contact a second point. The method can includerecording the position of the probe when the probe is contacting thesecond point. The method can include positioning the probe to contact athird point. The method can include recording the position of the probewhen the probe is contacting the third point. In some embodiments, thefirst point, the second point, and the third point define a plane, theplane can be rotated by the direction of gravity define an adjustedplane.

The method can include coupling the measuring device with a secondmeasuring device, wherein the second measuring device includes a digitaldisplay to provide an indication of positional changes of the probe. Insome embodiments, the first point is the ipsilateral ASIS. In someembodiments, the second point is the contralateral ASIS. The method caninclude positioning the probe horizontally to measure the direction ofgravity. The method can include determining cup angles relative to thereference plane. The method can include positioning a medical prosthesisat an angle relative to the adjusted plane. In some embodiments, thefirst point and the second point define the inter-ASIS line. In someembodiments, the first point, the second point, and the third pointdefine the anterior pelvic plane. In some embodiments, the third pointis the anterior surface of the pubic symphysis.

In some embodiments, a surgical system for assisting a surgeon inobtaining correct orientation of an acetabular prosthetic socket in apatient's acetabulum is provided. The instrument can include a supportdevice. The instrument can include a first electronic orientation devicehaving a coupler for releasably coupling the first electronicorientation device to the support device, wherein the first electronicorientation device comprises at least one inertial sensor. Theinstrument can include a probe assembly comprising a base portion and anelongate member configured to pivot and translate relative to the baseportion, wherein the elongate member has a length sufficient to enable atip thereof to contact anatomy disposed about the pelvis at a pluralityof discrete, spaced apart locations, the probe assembly comprising ansecond electronic orientation device, wherein the second electronicorientation device comprises at least one inertial sensor. In someembodiments, the first electronic orientation device and the secondelectronic orientation device are adapted to establish a reference planebased upon a direction of gravity and based upon the position of the atleast one inertial sensor when the tip contacts the plurality of spacedapart locations.

In some embodiments, the at least one inertial sensor of the firstelectronic orientation device or the at least one inertial sensor of thesecond electronic orientation device comprises an accelerometer. In someembodiments, the reference plane comprises the inter-ASIS line. In someembodiments, the first electronic orientation device includes a displayconfigured to provide an indication of the change in angular position ofthe second electronic orientation device relative to the referenceplane.

In some embodiments, a hip joint navigation system is provided. Thesystem can include a jig assembly. The system can include a firstinertial navigation device configured to be immovably coupled to the jigassembly. The system can include a landmark acquisition probe configuredto be movably coupled to the jig assembly, the landmark acquisitionprobe configured to move in a plurality of degrees of freedom relativeto the jig assembly. The system can include a second inertial navigationdevice configured to determine the orientation of the landmarkacquisition probe when the landmark acquisition probe is moved to touchan anatomical landmark. In some embodiments, the first inertialnavigation device, the second inertial navigation device, or the firstinertial navigation device and the second inertial navigation device areconfigured to adjusts for tilt by rotating the Anterior Pelvic Planeabout the inter-ASIS line to determine a reference plane.

In some embodiments, the second inertial device comprises a mount deviceconfigured to detachably connect the second inertial device to thelandmark acquisition probe. In some embodiments, the second inertialdevice comprises a camera. In some embodiments, the first inertialnavigation device comprises a display.

In some embodiments, a method of positioning a medical prosthesis isprovided. The method can include establishing a vertical plane with ameasuring device. The method can include positioning a probe to contacta point. The method can include recording a position of the probe whenthe probe is contacting the point before replacing a joint. The methodcan include recording a second position of the probe when the probe iscontacting the point after replacing the joint. In some embodiments, acomparison between the first position and the second position indicatesa change in leg length or joint offset.

The method can include coupling the measuring device and the probe to apatient. In some embodiments, the point is a structure. In someembodiments, the point is a burr. In some embodiments, the point is ananatomical landmark. The method can include determining cup anglesrelative to the vertical plane. The method can include positioning amedical prosthesis at an angle relative to the vertical plane. Themethod can include manually repositioning the femur after replacing thejoint. The method of claim 1, further comprising establishing ahorizontal plane with a measuring device, wherein the vertical plane andthe horizontal plane define a reference frame.

In some embodiments, a method of positioning a medical prosthesis isprovided. The method can include establishing a vertical plane with ameasuring device. The method can include projecting a pattern of lightonto the leg of a patient. The method can include recording theincidence of light on the leg of a patient. The method can includereplacing the joint by inserting a cup, wherein one or more angles ofthe cup are measured relative to the vertical plane. The method caninclude projecting the pattern light onto the leg of the patient afterreplacing the joint. The method can include repositioning the leg toalign the recording of the incidence of light with the pattern of light.The method can include recording a position of a probe when contacting apoint pre-dislocation. The method can include recording a position of aprobe when contacting a point post-instrumentation. The method caninclude determining a change in leg length. The method can includedetermining a change in leg length in the vertical plane. The method caninclude determining a change in joint offset. The method can includedetermining a change in joint offset in a plane perpendicular to thevertical plane. The method can include establishing a horizontal planewith a measuring device, wherein the vertical plane and the horizontalplane define a reference frame. The method can include recording a pointin the reference frame. The method can include recording a pointpre-operatively in the reference frame. The method can include recordinga point post-operatively in the reference frame.

In some embodiments, a surgical system for assisting a surgeon inobtaining correct orientation of an acetabular prosthetic socket in apatient's acetabulum is provided. The surgical system can include asupport device. The surgical system can include a first electronicorientation device having a coupler for releasably coupling the firstelectronic orientation device to the support device. In someembodiments, the first electronic orientation device comprises at leastone inertial sensor. In some embodiments, the first electronicorientation device and the second electronic orientation device areadapted to establish a reference plane based upon a direction ofgravity.

The surgical system can include a probe assembly comprising a baseportion and an elongate member configured to pivot and translaterelative to the base portion. In some embodiments, the probe assemblycomprises an second electronic orientation device. In some embodiments,the second electronic orientation device comprises at least one inertialsensor. In some embodiments, the first electronic orientation device andthe second electronic orientation device are adapted to record a pointwhen the probe contacts a point. In some embodiments, the firstelectronic orientation device and the second electronic orientationdevice are adapted to record a point when the probe contacts a pointpre-operatively and post-operatively. In some embodiments, the at leastone inertial sensor of the first electronic orientation device or the atleast one inertial sensor of the second electronic orientation devicecomprises an accelerometer. In some embodiments, the reference planecomprises a vertical plane. In some embodiments, the first electronicorientation device includes a display configured to provide anindication of the change in angular position of the second electronicorientation device relative to the reference plane. The surgical systemcan include an optical component configured to project a pattern oflight.

In some embodiments, a hip joint navigation system is provided. The hipjoint navigation system can include a jig assembly. The hip jointnavigation system can include a first inertial navigation deviceconfigured to be immovably coupled to the jig assembly. The hip jointnavigation system can include an optical component configured to projecta pattern of light. In some embodiments, incidence of the pattern oflight can be record to assist the user in realigning the femur to apre-operative position. The hip joint navigation system can include asecond inertial navigation device configured to determine theorientation of a probe when the probe is moved to touch a point.

In some embodiments, the pattern of light is a cross-hair. In someembodiments, the pattern of light is two lines. In some embodiments, thepattern of light is three points. In some embodiments, the opticalcomponent is configured to couple to the jig assembly with one or moremagnets. The hip joint navigation system can include a target probe forrecording or displaying the pattern of light, wherein the target probecomprises an anatomical contact portion and a target portion. In someembodiments, the anatomical contact portion and a target portion areseparate component. In some embodiments, the anatomical contact portioncomprises an incision drape.

In some embodiments, a hip joint navigation system is provided. The hipjoint navigation system can include an impactor. The hip jointnavigation system can include a coupler configured to be immovablycoupled with and to be decoupled from the impactor. The hip jointnavigation system can include an inertial navigation device configuredto be immovably coupled to the coupler. In some embodiments, theinertial navigation device is configured to determine the orientation ofthe impactor as the impactor is moved.

The hip joint navigation system can include a universal impactor adaptorcomprising the coupler. In some embodiments, the universal impactoradaptor is configured to be removably coupled to the impactor. In someembodiments, the universal impactor adaptor comprises a clamp. In someembodiments, the universal impactor adaptor comprises a magnet.

In some embodiments, a method of positioning a medical prosthesis isprovided. The method can include coupling a measuring device and probeto a patient. The method can include positioning the probe to contact afirst point. The method can include recording the position of the probewhen the probe is contacting the first point. The method can includepositioning the probe to contact a second point. The method can includerecording the position of the probe when the probe is contacting thesecond point. The method can include positioning the probe to contact athird point. The method can include recording the position of the probewhen the probe is contacting the third point. In some embodiments, thefirst point, the second point, and the third point define a plane, theplane can be rotated by the direction of gravity define an adjustedplane.

The method can include coupling the measuring device with a secondmeasuring device, wherein the second measuring device includes a digitaldisplay to provide an indication of positional changes of the probe. Insome embodiments, the first point is the ipsilateral ASIS. In someembodiments, the second point is the contralateral ASIS. The method caninclude positioning the probe horizontally to measure the direction ofgravity. The method can include determining cup angles relative to thereference plane. The method can include positioning a medical prosthesisat an angle relative to the adjusted plane. In some embodiments, thefirst point and the second point define the inter-ASIS line. In someembodiments, the first point, the second point, and the third pointdefine the anterior pelvic plane. In some embodiments, the third pointis the anterior surface of the pubic symphysis.

In some embodiments, a surgical system for assisting a surgeon inobtaining correct orientation of an acetabular prosthetic socket in apatient's acetabulum is provided. The surgical system can include asupport device. The surgical system can include a first electronicorientation device having a coupler for releasably coupling the firstelectronic orientation device to the support device. In someembodiments, the first electronic orientation device comprises at leastone inertial sensor. The surgical system can include a probe assemblycomprising a base portion and an elongate member configured to pivot andtranslate relative to the base portion. In some embodiments, theelongate member has a length sufficient to enable a tip thereof tocontact anatomy disposed about the pelvis at a plurality of discrete,spaced apart locations. In some embodiments, the probe assemblycomprises an second electronic orientation device. In some embodiments,the second electronic orientation device comprises at least one inertialsensor. In some embodiments, the first electronic orientation device andthe second electronic orientation device are adapted to establish areference plane based upon a direction of gravity and based upon theposition of the at least one inertial sensor when the tip contacts theplurality of spaced apart locations.

In some embodiments, the at least one inertial sensor of the firstelectronic orientation device or the at least one inertial sensor of thesecond electronic orientation device comprises an accelerometer. In someembodiments, the reference plane comprises the inter-ASIS line. In someembodiments, the first electronic orientation device includes a displayconfigured to provide an indication of the change in angular position ofthe second electronic orientation device relative to the referenceplane.

In some embodiments, a hip joint navigation system is provided. The hipjoint navigation system can include a jig assembly. The hip jointnavigation system can include a first inertial navigation deviceconfigured to be immovably coupled to the jig assembly. The hip jointnavigation system can include a landmark acquisition probe configured tobe movably coupled to the jig assembly. In some embodiments, thelandmark acquisition probe is configured to move in a plurality ofdegrees of freedom relative to the jig assembly. The hip jointnavigation system can include a second inertial navigation deviceconfigured to determine the orientation of the landmark acquisitionprobe when the landmark acquisition probe is moved to touch ananatomical landmark. In some embodiments, the first inertial navigationdevice, the second inertial navigation device, or the first inertialnavigation device and the second inertial navigation device areconfigured to adjust for tilt by rotating the Anterior Pelvic Planeabout the inter-ASIS line to determine a reference plane.

In some embodiments, the second inertial device comprises a mount deviceconfigured to detachably connect the second inertial device to thelandmark acquisition probe. In some embodiments, the second inertialdevice comprises a camera. In some embodiments, the first inertialnavigation device comprises a display. In some embodiments, the secondinertial navigation is configured to couple to an impactor. The hipjoint navigation system can include a universal impactor adaptorcomprising a coupler, wherein the second inertial navigation isconfigured to couple to an impactor with the adaptor. In someembodiments, the universal impactor adaptor comprises a clamp. In someembodiments, the universal impactor adaptor comprises one or moremagnets. The hip joint navigation system can include an opticalcomponent. In some embodiments, the optical component is configured tocouple to the jig assembly with one or more magnets.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages are described belowwith reference to the drawings, which are intended to illustrate but notto limit the inventions. In the drawings, like reference charactersdenote corresponding features consistently throughout similarembodiments.

FIG. 1 is a perspective view of a hip navigation system applied to apatient.

FIG. 2 illustrates an exploded view of embodiments of a fixation base ofthe system of FIG. 1.

FIGS. 3A-3G illustrate various view of embodiments of a first assemblyof the system of FIG. 1.

FIGS. 4A-4F illustrate various view of embodiments of a second assemblyof the system of FIG. 1.

FIGS. 5A-5C illustrate various view of embodiments of an orientationsensing device of the system of FIG. 1.

FIG. 6A illustrates an embodiment of an optical component. FIGS. 6B-6Cillustrate an embodiment of an optical component.

FIG. 7 illustrates a hip navigation system.

FIGS. 8A-8B illustrate an embodiment of a fixation base of the system ofFIG. 7.

FIG. 9 illustrates an embodiment of a first assembly of the system ofFIG. 7.

FIGS. 10A-10D illustrate an embodiment of a second assembly of thesystem of FIG. 7.

FIG. 11 illustrates a configuration of positioning of a patient in aposterior approach.

FIG. 12A illustrates a configuration of and a manner of coupling ofcomponents of the system. FIG. 12B illustrates a configuration of thesystem with a calibration fixture. FIG. 12C illustrates embodiments ofcomponents described herein.

FIGS. 13A-13C illustrates the fixation base and fixation pins of thesystem of FIG. 7 coupled to the pelvis.

FIGS. 14A-14C illustrates the assembly of the system of FIG. 7.

FIGS. 15A-15C illustrates the adjustment of the system of FIG. 7including the optical component of FIG. 6A.

FIG. 16 illustrates an embodiment of table registration.

FIGS. 17A-17B illustrate an embodiment of point registration before cupplacement.

FIG. 18A illustrates an embodiment of an impactor including theorientation sensing device of FIGS. 5A-5C. FIG. 18A illustrates a hipprosthesis placement system. FIGS. 18B-18D illustrate embodiments of auniversal impactor adapter.

FIGS. 19A-19C illustrate an embodiment of point registration after cupplacement.

FIGS. 20A-20I illustrate embodiments of target probes.

FIG. 21 is an example of an x-ray that can be taken pre-operatively.

FIG. 22 illustrates the positioning of a patient prior to connection ofthe system of FIG. 1 in an anterior approach.

FIG. 23 illustrates a configuration of the system of FIG. 1 coupled withthe pelvis.

FIG. 24 illustrates anatomy of an anterior portion of the hip joint,including the pelvis and the proximal femur.

FIGS. 25A-25D illustrates method steps to identify the Anterior PelvicPlane.

FIGS. 26A-26D illustrates method steps to identify a table or otherhorizontal plane.

FIGS. 27A-27D illustrates method steps to calculate an Adjusted Plane.

FIGS. 28A-28B illustrate side views of the pelvis and the AnteriorPelvic Plane and the Adjusted Plane thereof. FIG. 28C illustrates a topview of these planes. FIGS. 28A-1 and 28B-1 are alternative views.

FIG. 29 illustrates a screen display of a surgical orientation device ofthe system of FIG. 1.

FIGS. 30A-30C illustrate a neutral and two tilt positions of the pelvis.

FIGS. 31A-31C illustrate a neutral and two rotation positions of thepelvis.

DETAILED DESCRIPTION

A variety of systems and methods are discussed below that can be used toimprove outcomes for patients by increasing the likelihood of properplacement of a medical prosthesis. These systems can be focused oninertial navigation techniques to establish a reference plane. Thesesystems can be focused on inertial navigation techniques to measure leglength and/or joint offset.

A. Systems for Anterior and Poster Approach

1. Hip Navigation System

FIG. 1 shows a hip navigation system 600 adapted to navigate a hip jointprocedure with reference to anatomical landmarks. The system 600 isshown mounted on a pelvis in FIG. 1, which is shown as a box forsimplicity. The system 600 can be mounted on a pelvis for a posteriorapproach as described herein. The system 600 can be mounted on a pelvisfor an anterior approach as described herein

The system 600 can include a fixation base 602, a first assembly 604,and a second assembly 606. The first assembly 604 is rigidly connectedto the hip or pelvis in the illustrated configuration so that motion ofthe pelvis causes corresponding motion of sensor(s) in the firstassembly 604 as discussed herein. Sensing this motion enables the system600 to eliminate movement of the patient as a source of error in thenavigation. The second assembly 606 provides a full range of controlledmotion and sensor(s) that are able to track the motion, in concert withsensor(s) in the first assembly 604. Additional details of systems,devices, sensors, and methods are set forth in U.S. application Ser. No.10/864,085 filed Jun. 9, 2004, U.S. application Ser. No. 11/182,528filed Jul. 15, 2009 and related to U.S. Pat. No. 8,057,479, U.S.application Ser. No. 12/557,051 filed Sep. 10, 2009 and related to U.S.publication no. 2010/0076505, U.S. application Ser. No. 12/509,388 filedJul. 24, 2009, U.S. application Ser. No. 13/011,815 filed Jan. 21, 2011,U.S. application Ser. No. 13/115,065, filed May 24, 2011 and issued asU.S. Pat. No. 8,118,815; U.S. application Ser. No. 14/399,046 filed Nov.5, 2014, U.S. application Ser. No. 14/401,274 filed Nov. 14, 2014, U.S.application Ser. No. 13/800,620 filed Mar. 13, 2013, U.S. applicationSer. No. 14/643,864 filed Mar. 10, 2015 and U.S. application Ser. No.15/550,564 filed Aug. 11, 2017, which are all incorporated by referenceherein in their entireties for all purposes. The sensors in assemblies604, 606 preferably transfer data among themselves and in some caseswith external devices and monitors wirelessly, using Bluetooth, Wifi® orother standard wireless telemetry protocol. The system 600 can includeone or more fixation pins 610, 612. The system 600 can also include asurgical orientation device 172 and an orientation sensing device 204,as described herein.

The system 600 can include the fixation base 602 shown in FIG. 2. FIG. 2shows an exploded view of the fixation base 602. The fixation base 602can include a platform 620 and a support 622. The platform 620 caninteract with the support 622 to function as a clamp. In the illustratedembodiment, the fixation base 602 can include one or more fixationdevices 624 such as screws. The fixation devices 624 can pass throughthe support 622 and engage corresponding holes in the platform 620.

The platform 620 and the support 622 form one or more channelstherebetween. The number of channels can correspond to the number offixation pins. Upon rotation of the fixation devices 624, each fixationpin 610, 612 is retained between the platform 620 and the support 622.The fixation base 602 can include a divot 630. The divot 630 can beassociated with a parked configuration or home position, as describedherein.

The fixation base 602 can include a first coupler 632. The first coupler632 can couple to one or more components of the system 600. The firstcoupler 632 can include an elongate post 635. The first coupler 632 caninclude a slot 634. The slot 634 can be designed to interact withdetents of other components of the system 600, as described herein. Thefirst coupler 632 can include a tapered surface 636. The tapered surface636 can facilitate entry of the first coupler 632 within othercomponents of the system 600. In some embodiments, the first coupler 632can have a regular shape (e.g., cylindrical). In some embodiments, thefirst coupler 632 can have an irregular shape (e.g., triangular,teardrop, elliptical, rectangular). The irregular shape may facilitatealignment of other components of the system 600 with the platform 620 ofthe fixation base 602. In the illustrated embodiment, the othercomponents of the system 600 can mate with the first coupler 632 in asingle orientation.

The system 600 can include the first assembly 604 shown in FIGS. 3A-3G.The first assembly 604 can include a pelvic bracket 638. In theillustrated embodiment, the pelvic bracket 638 can be substantiallyvertical in use, as shown in FIG. 1. The first assembly 604 can bedesigned to couple with the fixation base 602. The first assembly 604can include a lock lever 640 to couple the first assembly 604 with thefixation base 602. In some embodiments, the tapered surface 636 of thefirst coupler 632 causes the pivoting of the lock lever 640. In someembodiment, the surgeon causes the pivoting of the lock lever 640. Thelock lever 640 can include a detent 642. The detent 642 is sized andshaped to be received within the slot 634. The engagement of the detent642 and the slot 634 can rigidly couple the first assembly 604 with thefixation base 602.

The first assembly 604 can include an extension 644. The extension 644can be coupled to the pelvic bracket 638. The extension 644 can includea second coupler 648. The second coupler 648 can be designed to couplewith the second assembly 606. The second coupler 648 provides a stablemanner to position the second assembly 606 relative to the firstassembly 604.

The extension 644 can include a mount 646 designed to couple with asurgical orientation device 172. The surgical orientation device 172 isrigidly coupled to the extension 644 when engaged with the mount 646.The surgical orientation device 172 can be angled when coupled to thefirst assembly 604, as shown in FIG. 1. The surgical orientation device172 can be angled approximately 35° from the horizontal axis. Otherangles from the horizontal axis are contemplated, (e.g., 5°, 10°, 15°,20°, 25°, 30°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, or 85°,between 30°-40°, between 25°-45°). In some embodiments, the angle of thesurgical orientation device 172 improves visibility. The angle is acompromise between tilting the surgical orientation device 172 up towardthe surgeon and allowing another surgeon or surgical assistant on theother side of the patient to still see the display. One reason forangling the surgical orientation device 172 is that in an anteriorapproach, the surgeon stands toward the patient's feet while impactingthe acetabular implant and a horizontal display may be difficult to see.

The surgical orientation device 172 detects orientation and rotation ofthe device 172 relative to a reference frame. The surgical orientationdevice 172 preferably comprises at least one sourceless sensor, such asan accelerometer, a gyroscope, or a combination of these sensors andother sensors. In some embodiments, the surgical orientation device 172includes a three axis accelerometer to detect orientation relative togravity and a plurality of gyroscopes to detect rotation. Other sensorscould be used in various modifications. Examples of specific sensorcombinations include Analog Devices ADIS 16445 and Invensense MPU-6050or MPU-9150 among others. In some approaches, the surgical orientationdevice 172 can be disposable and so the sensors preferably are lessexpensive sensors. In some embodiments, the surgical orientation device172 is disposable.

The surgical orientation device 172 includes one or more sensors thattogether form an inertial measurement unit (IMU). In particular, the IMUcan include a first sensor for determining acceleration and a secondsensor for determining gyroscopic positioning. As discussed herein, thefirst sensor can be an accelerometer and the second sensor can be agyroscopic sensor. In some embodiments, the sensors can comprise athree-axis gyroscopic sensor and a three-axis accelerometer sensor. Thesurgical orientation device 172 can include a transmitter for sendingdata or receiving data from one or more sensors of the system 600, suchas one or more sensors of the orientation sensing device 204. Theinformation received from the orientation sensing device 204 can be fedto an input port, or alternatively, the electronic control unit canitself receive the information (e.g., wirelessly). The information fromthe orientation sensing device 204 can correspond, for example, to theposition and/or orientation of the orientation sensing device 204 andcan be used by the surgical orientation device 172 to determine anaggregate, or overall, position and/or orientation of the surgicalorientation device 172.

The system 600 can include the second assembly 606 shown in FIG. 4A-4F.The second assembly 606 can include a probe bracket 652. In theillustrated embodiment, the probe bracket 652 can be substantiallyangled with respect to the pelvic bracket 638 when in use, as shown inFIG. 1. The second assembly 606 can be designed to couple with thesecond coupler 648 of the first assembly 604. The second assembly 606can include a lock lever 654. The lock lever 654 can be coupled to theprobe bracket 652 with pivot pins. The lock lever 654 can be pivotedrelative to the probe bracket 652. In some embodiments, the taperedsurface of the second coupler 648 causes the pivoting of the lock lever654. In some embodiments, the surgeon causes the pivoting of the locklever 654. The lock lever 654 can include a detent 656. The detent 656is sized and shaped to be received within the slot of the second coupler648. The engagement of the detent 656 and the slot can rigidly couplethe second assembly 606 with the first assembly 604.

In the illustrated embodiment, the second assembly 606 includes a mount658. The mount 658 can be coupled to the probe bracket 652 to allowrelative movement therebetween. The mount 658 can be received within anopening in the probe bracket 652. The mount 658 can permit rotationabout a longitudinal axis of the mount 658 relative to the probe bracket652.

The second assembly 606 can include a dock 662. The dock 662 can becoupled to the mount 658 to allow relative movement therebetween. Thedock 662 can be coupled to the mount 658 with one or more pivot pins660. The dock 662 can have two degrees of freedom relative to the probebracket 652 (e.g., rotational motion and pivoting motion). The dock 662can include a sliding support with a through lumen 664. The throughlumen 664 is sized to accept a probe 678. The probe 678 has a distal end680 designed to touch a point or a location or locations, as describedherein. The distal end 680 can be straight as shown in FIG. 4A. In otherembodiments, the distal end 680 is slanted or curved.

The through lumen 664 of the dock 662 permits slideable extension of theprobe 678. The dock 662 is movable relative to the probe bracket 652(e.g., via rotation of the mount 658 and pivoting of the pivot pin 660).The dock 662 can be rotated about a longitudinal axis of the mount 658to different rotational positions relative to the attachment location ofthe fixation pins 610, 612. This may require movement of the mount 658in a rotational manner relative to the probe bracket 652. The dock 662can be pivoted about the longitudinal axis of the pivot pins 660 todifferent positions relative to the attachment location of the fixationpins 610, 612. This may require movement of the dock 662 in a pivotingmanner relative to the mount 658.

The probe 678 can be coupled to the dock 662 such that the probe 678 ismovable relative to the probe bracket 652 (e.g., via rotation of themount 658 and pivoting of the pivot pin 660). This maneuverabilityenables the distal end 680 of the probe 678 to pivot or rotate tocontact anatomical landmarks, as discussed herein. The probe 678 can beslid relative to the dock 662 to different translational positionsrelative to the attachment location of the fixation pins 610, 612. Theslideability of the probe 678 within the dock 662 enables the distal end680 to move to reach a point or anatomical landmarks in the same planeof the probe 678 but closer to or farther from the distal end 680.

The second assembly 606 permits a range of motion of a distal end 680 ofthe probe 678 to facilitate acquiring a point that that is spaced apartfrom the attachment location of the fixation pins 610, 612. The secondassembly 606 permits a range of motion of a distal end 680 of the probe678 to facilitate acquiring a plurality of landmarks that are differentdistances from the attachment location of the fixation pins 610, 612. Inother words, the distal end 680 of the probe 678 can be extended awayfrom the axis of the sliding support of the dock 662 or can be retractedto a position closer to the axis of the sliding support of the dock 662.

The dock 662 can include a third coupler 668. In some embodiments, thethird coupler 668 is a universal coupler. In some embodiments, the thirdcoupler 668 is identical or substantially similar to the second coupler648. This permits the orientation sensing device 204 to couple to eitherthe second coupler 648 or the third coupler 668, as described herein. Insome embodiments, the third coupler 668 can be substantially similar tothe first coupler 632 described herein. The third coupler 668 can bedesigned to couple with the orientation sensing device 204. FIG. 5A-5Cillustrate an embodiment of the orientation sensing device 204. Thesecond assembly 606 can include an extension 670. The extension 670 cancouple to the third coupler 668 of the dock 662. The engagement betweenthe third coupler 668 and the extension 670 minimizes or preventsrelative movement therebetween to avoid any mechanical relative movementduring navigation procedures. The extension 670 can include a mount 672designed to couple with the orientation sensing device 204. In theillustrated embodiment, the mount 672 includes a lock and release leverthat can pivot relative to the extension 670. The orientation sensingdevice 204 can include features to mate with the lock and release lever.Other configurations are contemplated. The orientation sensing device204 is rigidly coupled to the extension 670 when engaged with the mount672.

The orientation sensing device 204 can be angled when coupled to thesecond assembly 606, as shown in FIG. 1. The orientation sensing device204 can be angled approximately 35° from the horizontal axis. Otherangles from the horizontal axis are contemplated, (e.g., 5°, 10°, 15°,20°, 25°, 30°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, or 85°,between 30°-40°, between 25°-45°). In some embodiments, the angle of theorientation sensing device 204 improves visibility.

The orientation sensing device 204 detects orientation and rotation ofthe probe 678, as described herein. The orientation sensing device 204preferably comprises at least one sourceless sensor, such as anaccelerometer, a gyroscope, or a combination of these sensors and othersensors. In some embodiments, the orientation sensing device 204includes a three axis accelerometer to detect orientation relative togravity and a plurality of gyroscopes to detect rotation. Other sensorscould be used in various modifications. In some embodiments, theorientation sensing device 204 is reusable.

Referring back to FIGS. 4A and 4C, the probe 678 can include a marking682. The marking 682 can indicate length or extension of the probe 678relative to the dock 662. The marking 682 can include a scale. In someembodiments, the marking 682 can be over a range of from about 8 inches,10 inches, 12 inches, approximately 8-12 inches, etc. The marking 682can be printed on the probe 678. In some embodiments, the marking 682can be on a separate component such as a probe inlay 676. The probeinlay 676 can be received within a portion of the probe 678. In someembodiments, the probe inlay 676 is separated a distance from the distalend 680 of the probe 678.

Referring to FIG. 5A-5C, the orientation sensing device 204 can includea camera 184. The camera 184 can capture images of the marking 682. Insome embodiments, the dock 662 includes a window to permit the camera184 to capture images. The camera 184 can read the marking 682 toprovide accurate determination of the translational position of theprobe 678 relative to the dock 662. In another embodiment, camera dataderived from the marking 682 can be used to confirm the data fromsensors in the orientation sensing device 204.

2. Optical Component

In some methods of use, the system 600 includes an optical component 174shown in FIG. 6A. In some embodiments, the optical component 174 isintegrated into the surgical orientation device. In some embodiments,the optical component 174 can be a separate component from the surgicalorientation device 172. The optical component 174 can be located belowthe surgical orientation device 172 adjacent to a fixture to be coupledwith a patient, e.g., closer to the pelvis of the patient. The opticalcomponent 174 can be located beside or adjacent to or above the surgicalorientation device 172. The display of the surgical orientation device172 can include instructions related to the method of using the opticalcomponent 174.

In some embodiments, the optical component 174 can include a housing.The optical component 174 can include one or more light sources withinthe housing of the optical component 174. The optical component 174 caninclude one or more windows which allow light to project outward fromthe optical component 174. The optical component 174 can include one ormore additional optical components such as one or more lens, one or morereflectors, one or more filters, one or more diffractor, and/or one ormore diffusors. The optical component 174 can include one or energysources to supply energy to the light source. The optical component 174can include any features of the surgical orientation device 172 and/orthe orientation sensing device 204 described herein.

In some embodiments, the optical component 174 is coupled to the system600. In some embodiments, the optical component 174 is coupled to thefirst assembly 604. In some embodiments, the optical component 174 canbe rotated, pivoted, or otherwise moved relative to the first assembly604. The system 600 can include additional features to facilitatepositioning of the optical component 174 relative to the first assembly604. The optical component 174 can include a bracket 176. The bracket176 can facilitate connection between the optical component 174 andanother component of the system 600. In some embodiments, the bracket176 can be a housing for the laser or other light source, describedherein. The optical component 174 can include one or more features toallow the independent adjustment of the optical component 174. Theoptical component 174 can include an adjustment feature 178. Theadjustment feature 178 can cause the rotation of the optical component174 relative to the first assembly 604. The adjustment feature 178 cancause the rotation of the optical component 174 relative to the secondassembly 606. The adjustment feature 178 can cause the rotation of theoptical component 174 relative to the fixation base 602. The adjustmentfeature 178 can cause the rotation of the optical component 174 relativeto the pelvis. The adjustment feature 178 can be a knob. The adjustmentfeature 178 can be coupled to an axle to cause rotation of the opticalcomponent 174 about the axle. The adjustment feature 178 can be coupledto the bracket 176 to cause rotation of the bracket 176. The bracket 176can include a sleeve or tubular portion designed to fit around an axleof the adjustment feature 178. In some embodiments, the opticalcomponent 174 is coupled independently to the bone of the patient. Theoptical component 174 can be coupled to the pelvis. Other configurationsof the optical component are contemplated, see FIG. 12C.

FIGS. 6B-6C illustrate another embodiment of an optical component 194.The optical component 194 can include one or more magnets 196. The oneor more magnets 196 can be located on a surface of the optical component194. The one or more magnets 196 can be disposed in or on a housing 200of the optical component 194. In some embodiments, the optical component194 can include one magnet, two magnets, three magnets, four magnets,etc. In some embodiments, the optical component 194 can include one ormore magnets on a first surface 202 and one or more magnets on a secondsurface 204. The first surface 202 can be located on an opposite side asthe second surface. In some embodiments, the optical component 194 caninclude one or more magnets on opposite sides of the optical component194. In some embodiments, the one or more magnets 196 on opposite sidesof the optical component 194 can allow the optical component 194 to becoupled with another component of any of the systems disclosed herein oneither side of the optical component 194.

In some embodiments, the optical component 194 is coupled to the system600. In some embodiments, the optical component 194 is coupled to thefirst assembly 604. In some embodiments, the first assembly 604 caninclude one or more magnets 198. The one or more magnets 198 can belocated on a surface of the first assembly 604. The one or more magnets198 can be disposed in or on an outer flat surface of the first assembly604. In some embodiments, the first assembly 604 can include one magnet,two magnets, three magnets, four magnets, etc. In some embodiments, thefirst assembly 604 includes one or more magnets 198 on a first surfaceand one or more magnets 198 on a second surface. In some embodiments,the first assembly 604 can include one or more magnets on opposite sidesof the first assembly 604. In some embodiments, the optical component194 can couple to either side of the first assembly 604. The one or moremagnets 198 of the first assembly 604 can correspond in number, size,shape and/or pattern to the one or more magnets 196 of the opticalcomponent 194. The one or more magnets 196 of the optical component 194can be configured to attract and couple to the one or more magnets 198of the first assembly 604. In some embodiments, the first assembly 604,or a portion thereof, comprises a magnetic material. In someembodiments, the entire first assembly 604 is magnetic. In someembodiments one or more magnets 198 can be configured to attract amagnetic material disposed on or in the housing of the optical component194. Accordingly, magnets may be positioned in or on the opticalcomponent 194, in or on the first assembly 604, or on or in both thecomponent 194 and the assembly 604.

In some embodiments, the optical component 194 can be held in positionrelative to the first assembly 604 with the one or more magnets 196,198. In some embodiments, the optical component 194 can be removablycoupled and decoupled from the system 600. In some embodiments, theoptical component 194 can allow for independent rotational adjustment ofthe optical component 194 relative to the system 600. In someembodiments, the optical component 194 can connect to the system 600 ina single orientation. In some embodiments, the optical component 194 canconnect to the system 600 in one of a plurality of orientations. In someembodiments, the optical component 194 can connect to the system 600 oneither side of the first assembly 604. As described herein, the opticalcomponent 194 can include one or more magnets 196 on opposite sides ofthe optical component 194. The first assembly 604 can include one ormore magnets 198 or magnetic surfaces on opposite sides of the firstassembly 604.

In some embodiments, the optical component 194 and the first assembly604 can include one or more mounting features 190, 192. The mountingfeatures 190, 192 can include one or more recesses 190 and one or moreprotrusions 192. In some embodiments, the first assembly 604 can includeone or more protrusions 192 and the optical component 194 can includeone or more corresponding recesses 190. In some embodiments, the firstassembly 604 can include two protrusions 192 and the optical component194 can include two or more recesses 190. In the illustrated embodiment,the first assembly 604 includes two protrusions 192 and the opticalcomponent 194 includes three recesses 190. The two protrusions 192 canengage two of the recesses 190 in a first configuration and two of therecesses in a second configuration. In embodiments, including threerecesses 190 and two protrusions 192, one of the recesses 190 is engagedin both the first and second configurations. The first configuration andthe second configuration can tilt the optical component 194 relative tothe first assembly 604. Other configurations are contemplated (e.g., oneprotrusion, two protrusions, three protrusions, four protrusions, etc.)and (e.g., one recess, two recesses, three recesses, four recesses, fiverecesses, six recesses, etc.). In some embodiments, there are morerecesses 190 than protrusions 192. The mounting features 190, 192 canreduce or limit rotation between the optical component 194 and the firstassembly 604. The mounting features 190, 192 can facilitate alignmentbetween the optical component 194 and the first assembly 604. Themounting features 190, 192 can facilitate the connection between theoptical component 194 and the first assembly 604. The one or moremagnets 196 of the optical component 194 can allow for quicker andsimpler attachment to the system 600. The one or more magnets 196 of theoptical component 194 can allow for a magnetic snap-on connection. Inother embodiments the polarity of the magnets 196 and/or the magnets 198can be configured such that only one or only two relative positions ofthe optical component 194 and the assembly 604 result in attraction andmagnetic securement therebetween. Other types of connections between theoptical components and the systems described herein are contemplated.

In some embodiments, the optical component 174, 194 can be positioned atany one of a plurality of discrete positions relative to the firstassembly 604. For instance, the system 600 can include a plurality ofsplines between the optical component 174, 194 and an adjacentstructure. The plurality of splines can be a serrated plate. Theadjacent structure can be coupled to the first assembly 604. Theplurality of splines can retain the position of the optical component174, 194 relative to the first assembly 604. In some embodiments, theoptical component 174, 194 can be oriented at an infinite number ofpositions relative to the first assembly 604. In some embodiments, theoptical component 174, 194 can be oriented at a select position along acontinuum of motion. In some embodiments, the optical component 174, 194can be oriented at one discrete position or orientation relative to thefirst assembly 604. In some embodiments, the optical component 174, 194can be oriented at two discrete positions or orientations relative tothe first assembly 604. In some embodiments, the optical component 174,194 can be oriented at one discrete position or orientation on each sideof the first assembly 604. In some embodiments, the optical component174, 194 can be oriented at a plurality of discrete positions ororientations relative to the first assembly 604. The connection betweenthe optical component 174, 194 and the first assembly 604 issufficiently rigid to maintain the position of the optical component174, 194 relative to the first assembly 604 once moved into position.

As described herein, in some methods of use, the optical component 174,194 is mounted to the pelvis of the patient. In some embodiments, theoptical component 174, 194 can be mounted to any component of the system600. In some embodiments, the optical component 174, 194 can be mountedto the platform 602. In some embodiments, the optical component 174, 194can be mounted to the first assembly 604. In some embodiments, theoptical component 174, 194 can be separately mounted to the pelvis. Insome methods of use, the optical component 174, 194 can be independentlymounted to the pelvis of the patient. In some methods of use, theoptical component 174, 194 can be spaced apart from the system 600. Insome methods of use, the optical component 174, 194 can be fixed inposition relative to the pelvis during the surgical procedure. In somemethods of use, the optical component 174, 194 can project light fromthe same position during the surgical procedure. The rigidity of thesystem 600 can secure the position of the optical component 174, 194once moved into position. In some methods of use, the optical component174, 194 can be positioned and/or moved until the optical component 174,194 projects light on a selected portion of the anatomy. In some methodsof use, the optical component 174, 194 can be positioned and/or moveduntil the optical component 174, 194 projects light on a target probe,as described herein. In some methods of use, the optical component 174,194 can be positioned and/or moved until the optical component 174, 194projects light on sterile wrap, medical drape, bandage, tape, and/orother instruments. In some methods of use, the optical component 174,194 can be positioned and/or moved until the optical component 174, 194projects light on a device coupled to the anatomy. In some methods ofuse, the optical component 174, 194 can be positioned and/or moved untilthe optical component 174, 194 projects light on a device placed nearthe anatomy, as described herein.

The optical component 174, 194 can emit a pattern of light. Examples ofpatterns of lights include one or more lines, one or more points, one ormore plane, or one or more shapes. The optical component 174, 194 can bemoved until the light is projected on at least one anatomical region. Insome methods of use, the light is projected onto at least one anatomicalregion with little soft tissue. The soft tissue may move relative to theunderlying bone. The surgeon can select locations to illuminate wherethe skin is close to the underlying bone. In some methods of use, theoptical component 174, 194 can project a pattern onto a portion of theanatomy. In some methods of use, the optical component 174, 194 canproject a pattern onto a target coupled to the anatomy. The surgeon cancomplete any method steps described herein. Thereafter, the opticalcomponent 174, 194 can project the same pattern on the selected portionof the anatomy.

In some embodiments, the optical component 174, 194 can project lightonto an anatomical surface. In some embodiments, the optical component174, 194 can project light onto an anatomical feature or landmark. Thelight can illuminate a portion of the femur. The light can illuminate aportion of the knee joint. The light can illuminate a portion of thetibia. The light can illuminate can illuminate a portion of the ankle.The light can illuminate a portion of the foot. The light can illuminatea portion of the foot constrained within a positioning boot. In someembodiments, the light can be projected onto a flat or substantiallyflat local area. In some embodiments, the light can be projected onto acurved or substantially curved local area. In some methods of use, theshape of the surface does alter the projection of light, e.g., changesin angle, tilt, shape, etc. In some methods of use, the shape of thesurface does not alter the projection of light. In some methods of use,the shape of the surface does not alter the utility of the approach, asdescribed herein.

In this context, optical component is a broad term. The opticalcomponent 174, 194 can be any device designed to project light includingvisible, ultraviolet, and infrared light. The optical component 174, 194can comprise one or more lasers, which can be configured to projectlaser light. The laser can emit light with a very narrow spectrum, forinstance a single color of light. The optical component 174, 194 canfocus light on a single location, such as a point. The optical component174, 194 can focus light along a line. The optical component 174, 194can project one or more points, one or more lines, one or more planes,one or more shapes, one or more colors, and/or one or more patterns. Insome embodiments, the projection of light when incident on a surface isvisible as two intersecting lines, the pattern may be referred to hereinas a cross-hair.

The optical component 174, 194 can be positioned to project light towarda desired location. The optical component 174, 194 can provide a visualguide to replicate an original position of an anatomical featurerelative to another anatomical feature, as described herein. In methodswherein the optical component 174, 194 is mounted to the pelvis, theoptical component 174, 194 can provide a visual guide to replicate theoriginal position of the leg or a portion thereof relative to the hip.In some embodiments, the optical component 174, 194 can provide a visualguide to replicate the original position of the femur relative to thepelvis as described herein. The optical component 174, 194 can providealternative or additional orientation information to a surgeon regardingthe position on the pelvis relative to the femur. In methods wherein theoptical component 174, 194 is mounted to the pelvis, the opticalcomponent 174, 194 can provide a visual guide to replicate the originalorientation of the leg or a portion thereof relative to the hip. In someembodiments, the optical component 174, 194 can provide a visual guideto replicate the original orientation of the femur relative to thepelvis as described herein. The optical component 174, 194 can providealternative or additional orientation information to a surgeon regardingthe orientation on the pelvis relative to the femur.

The optical component 174, 194 can be used to perform one or moremethods or method steps. In some methods of use, the optical component174, 194 can project the pattern of light pre-operatively. In somemethods of use, the optical component 174, 194 can project the patternof light before cup placement. In some methods of use, the opticalcomponent 174, 194 can project the pattern of light before jointreplacement. In some methods of use, the optical component 174, 194 canproject the pattern of light before joint dislocation. In some methodsof use, the optical component 174, 194 can project the pattern of lightthat can be traced. In some methods of use, the optical component 174,194 can project the pattern of light after cup placement. In somemethods of use, the optical component 174, 194 can project the patternof light post-instrumentation. In some methods of use, the opticalcomponent 174, 194 can project the pattern of light that can align witha marking as the femur is moved. In some methods of use, the opticalcomponent 174, 194 can project the pattern of light onto the samesurface before and after the cup is replaced. In some methods of use,the optical component 174, 194 can project the pattern of light onto thesame surface intra-operatively. In some methods of use, the opticalcomponent 174, 194 can project the pattern of light onto the samesurface intra-operatively at two or more times during the procedure.

3. Alternative Hip Navigation System

FIG. 7 illustrates a hip navigation system 700. FIGS. 8A-8B illustratean embodiment of a fixation base 702 of the system 700 of FIG. 7. FIG. 9illustrates an embodiment of a first assembly 704 of the system 700 ofFIG. 7. FIGS. 10A-10D illustrate an embodiment of a second assembly 706of the system 700 of FIG. 7.

The system 700 can include any of the features described herein withrespect to system 600. Similar elements are provided with similarreference numbers. The system 700 can include a fixation base 702, afirst assembly 704, and a second assembly 706. The system 700 caninclude the surgical orientation device 172 and the orientation sensingdevice 204. The orientation sensing device 204 can include a camera 184as shown in FIG. 5A. The system 700 can include an optical component 174as shown in FIG. 6A and/or the optical component 194 shown in FIGS.6B-6C. The optical component 174 can include one or more of thefollowing features: a bracket 176 and an adjustment feature 178 (seeFIG. 6A). The optical component 194 can include one or more of thefollowing features: one or more magnets 196 and one or more mountingfeatures 190, 192 (see FIGS. 6B-6C).

Referring to FIGS. 8A-8B, the fixation base 702 can include one or moreof the following: a platform 720, a support 722, one or more fixationdevices 724, a divot 730, and a first coupler 732 with a slot 734 and atapered surface 736. The system 700 can include one or more fixationpins, such as a fixation pin 710 and a fixation pin 712 (see FIGS.13A-13C).

Referring to FIG. 9, the first assembly 704 can include one or more ofthe following: a pelvic bracket 738, a lock lever 740, a detent 742sized and shaped to be received within the slot 734 (see FIG. 3A forsimilar detent 642), an extension 744, a second coupler 748 and a mount746 designed to couple with a surgical orientation device 172.

Referring to FIGS. 10A-10B, the second assembly 706 can include one ormore of the following: a probe bracket 752, a lock lever 754, a detent756 (see FIG. 4A for similar detent 656), a mount 758 to permit rotationabout a longitudinal axis of the mount 758 relative to the probe bracket752, a dock 762 coupled to the mount 758, a through lumen 764 sized toaccept a probe 778, a third coupler 768, an extension 770 (see FIG. 7),and a mount 772 (see FIG. 7). The orientation sensing device 204 cancouple to either the second coupler 748 or the third coupler 768.Referring to FIGS. 10C-10D, the system 700 can include the probe 778.The probe 778 can include one or more of the following: a distal end 780designed to touch a point, a marking 782, and a probe inlay 776.

The system 700 can include additional features from the system 600described herein. The system 600 can include one or more of theseadditional features. Referring back to FIGS. 8A-8B, the platform 720 caninclude an articulation 726. The articulation 726 can allow movementbetween the platform 720 and the first assembly 704. The articulation726 can form a ball and socket joint with the platform 720. Thearticulation 726 can include a head 728. The head 728 can interact withthe platform 720 to form a joint. In the illustrated embodiment, theplatform 720 includes the socket.

The articulation 726 can include the first coupler 732. The firstcoupler 732 can couple to one or more components of the system 700. Insome embodiments, the first coupler 732 is a universal coupler. Thefirst coupler 732 can include an elongate post 735. In some embodiments,the first coupler 732 can have a regular shape (e.g., cylindrical). Insome embodiments, the first coupler 732 can have an irregular shape(e.g., triangular, teardrop, elliptical, rectangular). The irregularshape may facilitate alignment of other components of the system 700with the platform 720 of the fixation base 702. In the illustratedembodiment, the other components of the system 700 can mate with thefirst coupler 732 in a single orientation. The articulation 726 caninclude the divot 730. The divot 730 can be associated with a parkedconfiguration or home position, as described herein.

The fixation base 702 can include the platform 720 and the support 722.The platform 720 can interact with the support 722 to function as aclamp. In the illustrated embodiment, the fixation base 702 can includeone or more fixation devices 724. In the illustrated embodiment,fixation base 702 includes two fixation devices 724. The fixationdevices 724 can pass through the support 722 and engage correspondingholes in the platform 720. Upon advancement of the fixation devices 724,each fixation pin 710, 712 is clamped between the platform 720 and thesupport 722. In some embodiments, the fixation devices 724 are screws,but other configurations are contemplated to clamp the platform 720 andthe support 722.

The articulation 726 can be locked in position. The fixation base 702can include a lock 727. The lock 727 can be advanced against the head728 to reduce, limit, or prevent movement of the articulation 726. Thelock 727 can include fastener such as a screw. In some embodiments, thelock 727 can include a contacting surface 729. The fastener can berotated or translated to advance the contacting surface 729 relative tothe platform 720. The contacting surface 729 can be moved away from thehead 728 to enable the head 728 to articulate with the platform 720. Thecontacting surface 729 can be moved toward the head 728 to apply a forceor pressure on the head 728. The contacting surface 729 can be movedtoward the head 728 push the head 728 against a surface of the platform720. The force or pressure of the contacting surface of the lock 727against the head 728 can reduce movement of the head 728. Otherconfiguration to reduce or prevent movement of the joint arecontemplated.

The articulation 726 is illustrated as a ball and socket joint. Thearticulation 726 can be any joint known in the art. The articulation 726can include an axle, a sleeve, a bearing, a bushing, and/or a swivel.The articulation 726 can be any joint or connection that allows motionabout one or more planes or axes. The articulation 726 can besufficiently rigid to maintain the position of the first assembly 704relative to the platform 720 once moved into position. Otherconfigurations are contemplated.

In some methods of use, the fixation base 702 is mounted to the pelvis,as described herein. The position of the pelvic bracket 738 of the firstassembly 704 can be adjusted via the articulation 726. The position ofthe extension 744 of the first assembly 604 can be adjusted via thearticulation 726. The optical component 174, 194 can be coupled to thefirst assembly 604 as described herein. The position of the opticalcomponent 174, 194 can be adjusted via the articulation 726. In someembodiments, the position of the optical component 174, 194 isdetermined in part by the position of the articulation 726. The system700 can have additional features to position of the optical component174, 194, as described herein. In other embodiments, the position of theoptical component 174, 194 is determined entirely by the position of thearticulation 726.

Referring now to FIGS. 10A-10D, the second assembly 706, or a portionthereof such as the probe 778, can be easily removed when not in use.The distal end 780 of the probe 778 can be angled, bent or curved tofacilitate acquiring a point. The distal end 780 of the probe 778 can bebent or curved to reach the home position. The shape of the probe 778can facilitate the touching of a point or structure in the posteriorapproach. In some embodiments, the probe 778 comprises two or morecomponents. In some embodiments, the distal end 680 is removable.

The second assembly 706 can include a dock 762. The dock 762 can becoupled to the mount 758 to allow relative pivotal movementtherebetween. For instance, the dock 662 can be coupled to the mount 758with one or more pivot pins 760. The dock 762 can have two degrees offreedom relative to the probe bracket 752 (e.g., rotational motion andpivoting motion). The dock 762 can include a sliding support with athrough lumen 764. The through lumen 764 is sized to accept a probe 778.The probe 778 has a distal end 780 designed to touch a point, asdescribed herein. The distal end 780 can be slanted or curved. Thismaneuverability enables the distal end 780 of the probe 778 to pivot,rotate, or slide to contact a point, as discussed herein.

The through lumen 764 of the dock 762 permits slideable extension of theprobe 778. The probe 778 can slide relative to the dock 762 to differenttranslational positions relative to the attachment location of thefixation pins 710, 712. The slideability of the probe 778 within thedock 762 enables the distal end 780 to move to reach a point in thewhich is offset from the plane of the probe 778 but closer to or fartherfrom the distal end 780.

The second assembly 706 can include a lock 766. The lock 766 can beadvanced against the probe 778 to reduce, limit, or prevent movement ofthe probe 778. The lock 766 can include fastener such as a screw. Insome embodiments, the lock 766 includes a contacting surface 767. Insome embodiments, the contacting surface 767 can be the end of thefastener. The fastener can be rotated or translated to advance thecontacting surface 767 relative to the dock 762. The contacting surface767 can be moved away from the probe 778 to enable the probe 778 toslide within the dock 762. The contacting surface 767 can be movedtoward the probe 778 to apply a force or pressure on the probe 778. Thecontacting surface 767 can be moved toward the probe 778 push the probe778 against a surface of the dock 762. The force or pressure of thecontacting surface 767 of the lock 766 against the probe 778 can reducemovement of the probe 778. The lock 766 can limit or reduce slidablilityof the probe 778 relative to the dock 762. In some methods of use, theprobe 778 can still pivot (e.g., pivotal motion between the dock 762 andthe mount 758). In some methods of use, the probe 778 can still rotate(e.g., rotational motion between the mount 758 and the probe bracket752). The lock 766 can reduce slidability when the point is registered,as described herein.

The system 700 can be utilized in the posterior approach as describedherein. The system 700 can be utilized in the anterior approach asdescribed herein.

B. Navigation for Cup Placement with Posterior Approach

1. Methods for Posterior Approach

FIGS. 1-10D illustrate hip navigation systems 600, 700 adapted tonavigate a hip joint procedure from a posterior approach. While themethod is described with respect to system 700, any systems describedherein or in the following publications can be utilized: U.S. Pat. Pub.No. 2016/0242934, filed Mar. 10, 2015; U.S. Pat. Pub. No. 2014/0052149filed Mar. 13, 2013; U.S. Pat. Pub. No. 2010/0137871 filed Sep. 10,2009, all of which are incorporated by reference in their entirety.

In some methods of cup placement in total hip arthroplasty, theinclination and anteversion angles are with respect to the AnteriorPelvic Plane (defined as a plane created by the two anterior superioriliac spines (ASIS) and the pubic symphysis). While these anatomicalfeatures are visible/palpable while the patient is in a supine position,the majority of total hip replacements are accomplished via aposterolateral approach with the patient in some variation of a lateralposition, in which most of these landmarks are not accessible orvisible. Historically, navigation for posterior approach hip replacementhas been accomplished by registering the anatomical features of theAnterior Pelvic Plane with the patient first in a supine position and,once this plane is recorded by the navigation computer, moving thepatient to a lateral position in order to perform hip surgery—withnavigation performed with respect to the directly registered AnteriorPelvic Plane. This approach to hip navigation is sub-optimal forsurgical workflow because the extra movement of the patient from supineto lateral position takes more surgeon and staff time and requiresbreaking sterility and re-draping. This is one of the key reasons whyhip navigation has failed to be adopted by most of the market.

Additionally, altered leg length is a common patient complaint arisingfrom hip replacement surgery and has been a common cause of medicalmalpractice lawsuits that arise from hip replacement. Because part ofthe hip replacement procedure requires precise measurements of patientleg length and joint off-set that are frequently difficult to visualizeutilizing conventional instrumentation, there are opportunities toimprove the surgeon's performance of these measurements using computertechnology.

Most hip replacement procedures presently are performed from a posteriorapproach. In this approach, the patient is positioned on his/her sideand the anterior pelvic plane is oriented vertically, e.g.,perpendicular to the plane of the table on which the patient ispositioned. Most surgeons performing hip replacement are very familiarwith this approach and will immediately recognize the benefit ofenhanced certainty about the orientation of the relevant anatomy whenthe patient is in this position.

As discussed herein, the method of use can include using the probe 778and the sensor 204 to estimate a horizontal plane of the surgical tableupon which the patient is resting. As discussed herein, the method ofuse can include using the probe 778 and the sensor 204 to estimate avertical plane utilizing a measurement of gravity. The system 700 canestablish a reference frame for guiding the placement of the cup withoutregistering landmarks. The system 700 can measure leg length and/orjoint offset within the established reference frame.

FIG. 11 shows an embodiment of the patient positioning for the posteriorhip approach. In the posterior hip approach, the patient can be placedon their side. In some methods of use, the patient can be placed in thelateral decubitus position. When positioning patient prior to surgery,the surgeon can align the anterior pelvic landmarks (both ASIS's andpubic tubercle) in a vertical plane parallel to the long edge of theoperating table. In some methods of use, when positioning patient priorto surgery, the surgeon can align the anterior pelvic landmarks (bothASIS's and pubic tubercle) in a vertical plane perpendicular to asurface of the table. In some methods of use, when positioning patientprior to surgery, the surgeon can align the anterior pelvic landmarks(both ASIS's and pubic tubercle) in a vertical plane parallel togravity. In some methods of use, when positioning patient prior tosurgery, the surgeon can align Anterior Pelvic Plane parallel togravity. In some methods of use, when positioning patient prior tosurgery, the surgeon can align Anterior Pelvic Plane vertically. Thesurgeon can ensure that pelvis is securely held by an appropriatepositioning device such as a peg board or vise-type patient positioner.The surgeon can verify that patient is positioned in an appropriateposition for the posterior approach. Correct patient positioning isimportant for accurate navigation. In some methods of use, the system700 calculates cup angles based on the assumption that the pelvis isaccurately positioned during table registration. In some methods of use,the system 700 calculates cup angles based on the assumption that theAnterior Pelvic Plane is vertical during the posterior procedure.

The surgical orientation device 172 and the orientation sensing device204 can be turned on before the procedure begins. If the system can beused in a knee or hip procedure, one method can involve a surgeonselecting a module corresponding to the hip. If the system can be usedin a posterior or anterior approach, one method can involve a surgeonselecting a module corresponding to the posterior approach. The surgicalorientation device 172 can include a display screen. The surgicalorientation device 172 can include a user interface, such as buttonswhich can be depressed by the user. The display screen can confirm thecommunication between the surgical orientation device 172 and theorientation sensing device 204.

The system 700 can be partially assembled for calibration. While thesystem 600 is shown in FIG. 12A, the system 700 can be similarlycoupled. In some embodiments, the first assembly 604, 704 can beassembled. The pelvic bracket 638, 738 can be coupled to the extension644, 744, if separate components. The surgical orientation device 172can be coupled to the mount 646, 746. In some techniques, the extension670, 770 can be coupled to the second coupler 648, 748. The orientationsensing device 204 can be coupled to the mount 672, 772. The surgicalorientation device 172 and the orientation sensing device 204 form ageneral V-shaped configuration, similar to the orientation shown in FIG.12A. The orientation sensing device 204 can be fixed in positionrelative to the surgical orientation device 172.

In some methods of use, the probe 778 can be calibrated. The extension770 can be decoupled from the second coupler 748. The second assembly706 can be assembled as shown in FIG. 12B. The first assembly 704 can becoupled to the second assembly 706 as shown in FIG. 12B. In some methodsof use, the system 700 can include a calibration fixture 790. The firstassembly 704 and the second assembly 706 can be mounted to thecalibration fixture 790. The calibration fixture can include a pluralityof points for the probe 778 to contact.

In some methods of use, the probe 778 can contact a center hole at thebase of the calibration fixture 790 to calibrate a center point. Theuser can depress a button when the probe 778 is placed. In some methodsof use, the probe 778 can contact a left hole at the base of thecalibration fixture 790 to calibrate a left point. The user can depressa button when the probe 778 is placed. In some methods of use, the probe778 can contact a right hole at the base of the calibration fixture 790to calibrate a right point. The user can depress a button when the probe778 is placed. The calibration fixture 790 can be utilized prior to theprocedure. The calibration fixture 790 can be located away from thepatient, for instance on a back table. Other calibration fixtures andjigs are contemplated.

The surgical orientation device 172 and the orientation sensing device204 can be calibrated. The surgical orientation device 172 can be restedon a level horizontal surface with the display horizontal (facing up).The surgeon can hold the assemblies 704, 706 steady until the surgicalorientation device 172 indicates completion. The orientation sensingdevice 204 can be rested on a level horizontal surface with the displayvertical (facing user). The surgeon can hold the assemblies 704, 706steady until the surgical orientation device 172 indicates completion.The surgical orientation device 172 can be rested on a level horizontalsurface with the display pointed sideways (left side). The surgeon canhold the assemblies 704, 706 steady until the surgical orientationdevice 172 indicates completion. The surgical orientation device 172 canbe rested on a level horizontal surface with the display horizontal(facing up) again. The surgeon can hold the assemblies 704, 706 steadyuntil the surgical orientation device 172 indicates completion. Otherorientations of the surgical orientation device 172 and the orientationsensing device 204 are contemplated for calibration.

The user can remove the required instruments and prepare the instrumentsfor use. FIG. 12C illustrates examples of components described herein.The optical component 174, 194 can be activated. In some embodiments,the optical component 174, 194 can include a movable cover or screen,such as a shutter. The user can close the shutter and insert a batteryinto the optical component 174, 194. In some embodiments, the opticalcomponent 174, 194 can be coupled to the first assembly 704 using one ormore fasteners. In some embodiments, the fastener is the adjustmentfeature 178. In some embodiments, the fastener can be secured using adriver 792, see FIG. 12C. In some embodiments, the optical component174, 194 is affixed to the first assembly 704 using a hex driver. Insome embodiments, the optical component 174, 194 is affixed to the firstassembly 704 using a ball driver. In some embodiments, the opticalcomponent 174, 194 can be affixed to the first assembly 704 using one ormore magnets as described in relation to FIGS. 6B-6C. In someembodiments, the optical component 174, 194 can be affixed to the firstassembly 704 using one or more removable coupling devices such as clips,straps, bayonet connection, etc., and/or non-removable coupling devicessuch as adhesive, integrally formed, monolithically formed, etc. Thesurgeon can ensure that the optical component 174, 194 is securelyattached and does not rotate on the first assembly 704. In someembodiments, the bracket 176 facilitates the coupling of the opticalcomponent and the first assembly 704. In some embodiments, theadjustment feature 178 facilitates the coupling of the optical componentand the first assembly 704. In some embodiments, the optical component174, 194 is coupled to the fixation base 702. In some embodiments, theoptical component is coupled to the fixation pins 710, 712. In someembodiments, the optical component is coupled to the second assembly606, 706. In some embodiments, the optical component 174, 194 is coupleddirectly to the pelvis. In some embodiments, the optical component 174,194 remains on as long as the battery is installed. The laser or otherlight emission is shown or hidden through the movement of the shutter.The optical component 174, 194 can include a marking to indicate thedirection of the emission. In some embodiments, the optical component174, 194 can include an arrow to indicate the direction of the laser.

The user can interact with the surgical orientation device 172. If thesystem 700 can be used in either hip procedure, one method can involve asurgeon selecting a module corresponding to the right hip or the lefthip. In some methods of use, the user can input a target cup abductionangle. This is the Radiographic Abduction angle defined as the coronalplane projection of the angle between the acetabular axis and thelongitudinal axis of the body. Abduction and adduction are also used todescribe movement of the limb within the coronal plane. In some methodsof use, the user can input a target cup anteversion angle. This is theRadiographic Anteversion angle defined as the angle between theacetabular axis and the coronal plane. The user can input target angleswhich can be stored by the surgical orientation device 172. In somemethods of use, these target angles are utilized by the surgicalorientation device 172 during cup placement.

The system 700 can be attached to the pelvis as shown in FIGS. 13A-13C.The user can position the system 700 such that the system 700 has solidand stable mount for attachment of the instrumentation to the pelvis. Insome methods of use, all measurements and references are based off theinitial registration process and any movement of the first assembly 704after will result in error in the resulting readouts of cup position,leg length, and/or joint offset. In some methods, the fixation pins 710,712 are placed in the ipsilateral iliac crest. Referring to FIG. 13A,for the first fixation pin 710, the surgeon can make a stab incisionover the ipsilateral iliac crest, directly superior to the greatertrochanter. The surgeon can insert the fixation pin 710. In someembodiments, the fixation pin 710 is a 4.0 mm threaded fixation pin. Thefixation pin 710 can be inserted vertically using a wire driver.Referring to FIG. 13B, the surgeon can make a second stab incision, andinsert the second fixation pin 710 in the iliac crest 2 cm anteriorparallel to the first pin 712. The surgeon can use the fixation base 702as a guide for spacing between the pins 710, 712. Referring to FIG. 13C,the surgeon can slide the fixation base 702 over both pins to the levelof the skin. The surgeon can use a driver to tighten the two fixationdevices 724 to secure fixation base 702 to the fixation pins 710, 712.In some methods of use, the fixation pins 710, 712 are placed in asimilar fashion to placement of pins for pelvic external fixation. Insome methods of use, the fixation pins 710, 712 enter the iliac wing atits most superior surface and travel between the tables of the inner andouter bone of the iliac wing. In some methods of use, the fixation base702 is attached prior to dislocating the hip to ensure correct patientpositioning and navigation accuracy. The surgeon can take steps to avoidplunging through the medial wall of the iliac wing. The surgeon canverify that fixation base 702 is securely mounted to the bone. Thesurgeon can minimize divergence or bending of fixation pins 710, 712.

The system 700 can be assembled as shown in FIG. 14A-14C. Referring toFIG. 14A, the orientation sensing device 204 can be coupled to the probe778. In some embodiments, the orientation sensing device 204 and/or theprobe 778 can include indicia such as arrows to facilitate alignment.Referring to FIG. 14B, the first assembly 704 can be secured to thefixation base 702 with the surgical orientation device 172 attached. Thefirst assembly 704 can be secured by pushing on the lock lever 740, asdescribed herein. Referring to FIG. 14C, the second assembly 706 can besecured to the fixation base 702 with the orientation sensing device 204attached. In some embodiments, the second assembly 706 and/or thefixation base 702 can include indicia such as arrows to facilitatealignment. The second assembly 706 can be secured by pushing on the locklever 754, as described herein. The optical component 174, 194 can besecured to the first assembly 704. In some embodiments, the opticalcomponent 174, 194 and/or the first assembly 704 can include indiciasuch as arrows to facilitate alignment.

The system 700 can be aligned as shown in FIG. 15A. The surgeon canplace the leg on the operative side in a neutral position. The surgeoncan open the shutter on the optical component 174, 194. The surgeon canalign the optical component 174, 194 so that the laser projects apattern of light. One example of the incidence of light is shown as 180.In some embodiments, the pattern of light includes two lines. In someembodiments, the pattern of light includes two intersecting lines. Insome embodiments, the pattern of light includes two perpendicular lines.In some embodiments, the pattern of light includes two parallel lines.In some embodiments, the pattern of light includes three points. In someembodiments, the pattern of light includes three points that form atriangle. In some embodiments, the pattern of light includes threepoints which do not lie on the same line. In some embodiments, thepattern of light is projected onto the leg. In some embodiments, thepattern of light is projected onto the knee. In some embodiments, thepattern of light is projected onto the distal foot. In some embodiments,the pattern of light is projected onto the distal thigh. In someembodiments, the pattern of light is projected onto a portion of the legincluding a sterile wrap.

The system 700 can be adjusted as shown in FIGS. 15B-15C. To adjust theprojection of the optical component 174, 194, the user can adjust thearticulation 726. To adjust the projection of the optical component 174,194, the user can adjust the adjustment feature 178 (see FIG. 6A). Toadjust the projection of the optical component 174, 194, the user canadjust the re-position of the fixation base 702. The surgeon can loosenthe fixation devices 724 to adjust the fixation base 702 as desired. Thesurgeon can adjust the articulation 726 to position the articulation 726as desired. The surgeon can adjust the bracket 176 and/or adjustmentfeature 178 to position the optical component as desired. The surgeoncan reposition any component of the system 700 as desired.

Once the system 700 is in the desired position, components of the system700 can be immobilized. The surgeon can tighten the fixation devices 724to secure the fixation base 702. The fixation base 702 can be secured tothe fixation pins 710, 712. In some methods of use, the fixation base702 remains in this position for the procedure. The articulation 726 canbe locked in position. The fixation base 702 can include the lock 727.The surgeon can advance the lock 727 against head 728 to preventmovement of the articulation 726. In some methods of use, the surgeoncan use a driver to rotate the lock 727. The driver can be a 3.5 mm hexdriver to advance the contact surface 729 against the head 728 of thearticulation 726. In some methods of use, the articulation 726 remainsin this position for the procedure. The surgeon can adjust the lock 727to reduce or prevent movement of the articulation 726. The opticalcomponent 174, 194 can be secured to the first assembly 704 and/or thefixation base 702. In some embodiments, the adjustment feature 178 canbe self-locking. The adjustment feature 178 can include a plurality ofdiscrete location. The adjustment feature 178 can lock when moved to oneof the plurality of discrete location. In some methods of use, theoptical component 174, 194 can remain immobilized during the rest of theprocedure. In some methods of use, the first assembly 604 can remainimmobilized during the rest of the procedure.

Referring to back to FIG. 15A, the method can include recording theincidence of the light 180. The surgeon can record the shape of theprojection. The surgeon can record the incidence of light from theoptical component onto a surface. The incidence of light can be theintersection of the light with an anatomical surface of the patient. Theanatomical surface can be any surface of the patient. The anatomicalsurface can be any surface on the leg. The method can include markingthe position of the light. The method can include the step of markingtwo or more points along a line of light. The method can include drawinga line along the line of light. The method can include capturing animage of the incidence of light. The method of use can include the stepof utilizing a camera to capture the incidence of light. In someembodiments, the surgeon traces the pattern of light. In someembodiments, the surgeon can make a mark on the femur, such as a boviemark, a pen mark, a stitch or other durable indication.

In some embodiments, the surgeon can mark the incidence of light 180. Insome embodiments, the surgeon can mark two lines. In some embodiments,the surgeon can mark two intersecting lines. In some embodiments, thesurgeon can mark two perpendicular lines. In some embodiments, thesurgeon can mark two parallel lines. In some embodiments, the surgeoncan mark a cross-hair. In some embodiments, the surgeon can mark theincidence of light from a projected pattern of light. In someembodiments, the surgeon can mark three points In some embodiments, thesurgeon can mark three points which do not lie on the same line. In someembodiments, the surgeon can mark three points which are localized on aregion of the leg. In some embodiments, the surgeon can mark threepoints which are projected onto femur. In some embodiments, the surgeoncan mark three points, one or more points lie on the femur. In someembodiments, the surgeon can mark three points, one or more points lieon the femur, tibia, knee, ankle, or foot, or any combination thereof.In some embodiments, the surgeon can mark onto the leg. In someembodiments, the surgeon can mark onto the knee. In some embodiments,the surgeon can mark onto the distal foot. In some embodiments, thesurgeon can mark onto the distal thigh. In some embodiments, the surgeoncan trace the pattern with a marker. In some embodiments, the surgeoncan trace the pattern onto the leg directly.

In some embodiments, the surgeon can trace the pattern on the sterilewrap. In some embodiments, the pattern of light is projected onto aportion of the leg including a sterile wrap. In some embodiments, thesurgeon traces the pattern of light on the sterile wrap. In someembodiments, the surgeon marks the two lines on the sterile wrap. Insome embodiments, the surgeon marks the three points on the sterilewrap.

In some embodiments, target probes can be provided for recording theincidence of light. FIGS. 20A-20I illustrates examples of target probes.FIGS. 20A-20B illustrate target probe 18 a and FIG. 20C-20D illustratestarget probe 18 b. At least one target probe 18 a, 18 b, or othertargets or devices, can comprise a structure for contacting the anatomyof a patient and serving as a target for an emitted light from theoptical component 174, 194. For example, in some embodiments, the atleast one target probe 18 a, 18 b can comprise an elongate member 106with an anatomical contact portion 107 and a target portion 108. Theanatomical contact portion 107 can comprise an end of the elongatemember 106 or other structure configured to contact an anatomicalfeature or surface. In some embodiments, the anatomical contact portion107 contacts the femur. In some embodiments, the anatomical contactportion 107 contacts the knee. In some embodiments, the anatomicalcontact portion 107 contacts the upper thigh. In some embodiments, theanatomical contact portion 107 can be held against the anatomicalfeature. In some embodiments, the anatomical contact portion 107 can bedrilled into the anatomical feature. In some embodiments, the anatomicalcontact portion 107 coupled with the anatomical feature.

The anatomical contact portion 107 can be connected to or integrallyformed with the target portion 108. The target portion 108 can comprisea surface which can be marked by the surgeon. The target portion 108 cancomprise a surface which can record the incidence of light. The targetportion 108 is configured to assist in recording the incidence of light.Aligning the incidence of light on the target portion 108 before andafter cup placement can assist in aligning the underlying anatomy beforeand after cup placement.

In some embodiments, the target portion 108 can comprise one or moretarget shapes 110, in the form of markings, slits, or other structures.In some methods of use, the target shapes 110 can be marked beforeplacement of the target 18 a, 18 b on the anatomy. In some methods ofuse, the target shapes 110 are marked by the surgeon after placement ofthe target 18 a, 18 b on the anatomy. In some methods of use, the targetshapes 110 are marked by the surgeon before cup placement. In somemethods of use, the target shapes 110, if for example in the form ofslots, can be wide enough to allow a beam of laser light, such as forexample a beam in the form of a plane or a cross-hair beam, to passthrough the target shapes 110. FIG. 20 illustrates an embodiment of atarget probe 18 b with a target shape 110 in the form of a single slot,and a target probe 18 a with two slots in the form of a cross, forexample formed as two perpendicular lines or slots. FIG. 20 canillustrate opposite sides of the same target probe. For example, oneside of the target probe can have a cross-hair target 110, and the otherside of the target probe can have a single slot target 110.

In some embodiments, the optical component 174, 194 is adjusted to alignthe incidence of light with the target 18 a, 18 b. In some embodiments,the system 700 is adjusted to align the incidence of light with thetarget 18 a, 18 b. For instance, the articulation 726 can be adjusted.In some embodiments, the target 18 a, 18 b is adjusted to align theincidence of light with the target portion 108 of the target 18 a, 18 b.The target portion 108 can be adjustable, such that as the anatomicalcontact portion 107 is held in place against the anatomical landmark,the target portion 108 can be moved relative to the anatomical landmark.For example, the target portion 108 can comprise a screw or otherelement which can be adjusted in order to change the length of thetarget probe 18 a, 18 b. In one embodiment, a device is provided toenable the position of the target portion 108 on the elongate member 106to be adjusted. The device enables the target portion 108 to be movedcloser to or away from the contact portion 106. Such adjustment providesone technique for aligning the incidence of light with the target 18 a,18 b. The target probes 18 a, 18 b can further include a marking ormarkings which indicate a current length of the target probe 18 a, 18 b,and/or indicate the degree or amount of adjustment which has been madeto the target probe 18 a, 18 b. For example, the target portion 108 cancomprise millimeter markings or other visual indicia corresponding tolengthwise offset along a length of the target portion 108, indicatingadjustments in the length of millimeters.

FIGS. 20E-20F illustrate an embodiment of target probe 18 c. In someembodiments, the target probe 18 c is not attached rigidly to the leg.In some embodiments, the target probe 18 c is held in position by theuser. FIG. 20E illustrates the target probe 18 c in position against theanatomy of the patient, and FIG. 20F illustrates the target probe 18 cbeing removed by the surgeon. In the illustrated embodiment, the leg iswrapped with an incise drape. The incise drape can be marked by theuser. The user has marked the longitudinal axis of the bone, as well asa home position for the target probe 18 c. These markings on the drapecan be performed when the surgeon marks the incidence of light on thetarget probe 18 c. The target probe 18 c can be oriented within the homeposition and the incidence of light can be marked. During the procedure,the user can align the marking with the marked longitudinal axis. Thesurgeon can adjust the anatomy until the incidence of light aligns withthe marking on the target 18 c. The target 18 c can be any shape toallow the marking of the incidence of light. In the illustratedembodiment, the target 18 c is generally L-shaped. In some embodiments,the target probe 18 c is removable during the surgery. The target probe18 c can be positioned on the leg. In some methods of use, one or moremarkings on the thigh 182 can aid in re-positioning of the target 18 c.The markings can include one or more lines, points, shapes, symbols,etc. In the illustrated embodiment, the markings on the thigh 182 caninclude a cross-hair or other pattern related to the incidence of light180. In some methods of use, the surgeon can position the target 18 cbefore and after cup replacement. In some methods of use, the surgeoncan mark the incidence of light before joint dislocation. In somemethods of use, the surgeon can reposition the femur after cup placementsuch that the incidence of light aligns with the markings.

FIG. 20G illustrates an embodiment of target probe 18 d. The targetprobe 18 d can comprise an anatomical contact portion 107 and a targetportion 108. The anatomical contact portion 107 can comprise a strap,clip, bracket, zip-tie or other structure configured to wrap around ananatomical feature or surface. In some embodiments, the anatomicalcontact portion 107 contacts the thigh. In some embodiments, theanatomical contact portion 107 contacts the knee. In some embodiments,the anatomical contact portion 107 contacts the shin. In someembodiments, the target portion 108 can be moved relative to theanatomical contact portion 107. The target portion 108 can be rotated,pivoted, and/or translated to position the target portion 108 relativeto the anatomical contact portion 107. In some embodiments, the targetportion 108 is fixed relative to the anatomical contact portion 107. Thetarget portion 108 can include one or more surfaces to mark theincidence of light.

FIGS. 20H-20I illustrate an embodiment of a target probe 18 e. Thetarget probe 18 e can comprise an anatomical contact portion 107 and atarget portion 108. The anatomical contact portion 107 can comprise abendable surface configured to adapt to and directly contact orindirectly couple with the anatomy of the patient. The contact portion107 can create a tri-fold shape or can be formed to a continuous curve.The contact portion 107 can include a portion to wrap around theanatomical feature or surface of the patient. In some embodiments thewrap is a separate component that is stretched or wrapped around thecontact portion 107. The contact portion 107 can include or be wrappedby an incise drape 109, such as an iodine-impregnated incision drape(Ioban® manufactured by 3M®). The incise drape 109 can provide strongadhesion to the surface of the skin. In some embodiments, the incisedrape 109 can provide antimicrobial properties for the reduction ofpost-operative wound infections. The contact portion 107 can be adheredor otherwise coupled to the incise drape 109 or to the leg prior towrapping the drape 109. The contact portion 107 can be integrally formedwith the incise drape 109. The target portion 108 can be integrallyformed with the contact portion 107. The target portion 108 can beintegrally formed with the incise drape 109. Other wraps or drapes arecontemplated. The contact portion 107 can by connected to the anatomy ofthe patient through any means. In some embodiments, the contact portion107 includes an adhesive. In some embodiments, the contact portion 107is adjustable, such as through the use of an adjustable adhesive orputty. In some embodiments, the contact portion 107 includes a tape orother medical wrap. In some embodiments, the contact portion 107includes one or more fixation pins.

In some embodiments, the incise drape 109 wraps around the thigh of thepatient. In some embodiments, the incise drape 109 wraps around the kneeof the patient. In some embodiments, the incise drape 109 wraps aroundthe shin of the patient. In some embodiments, the target portion 108 isfixed relative to the anatomical contact portion 107 and/or the incisedrape 109. In some embodiments, the target portion 108 can be movedrelative to the anatomical contact portion 107 and/or the incise drape109. The target portion 108 can be rotated, pivoted, and/or translatedto position the target portion 108 relative to the anatomical contactportion 107. The target portion 108 can include one or more surfaces tomark the incidence of light. The target probe 18 e can be a verticallaser target. The target portion 108 can extend from the skin of apatient in a vertical direction. The target portion 108 can extend fromthe skin of a patient in a horizontal direction.

The target probe 18 e can be formed of two pieces. The contact portion107 and the target portion 108 can be separate component. The contactportion 107 and the incise drape 109 can be separate components. Thetarget portion 108 and the incise drape 109 can be separate component.The contact portion 107 and/or the incise drape 109 can be rigidlyaffixed to the body of the patient. In some embodiments, the contactportion 107 and/or the incise drape 109 can be permanently fixed, or atleast permanently fixed during the duration of the procedure. Thecontact portion 107 and/or the incise drape 109 can be affixed to thethigh to form a self-supporting structure with the thigh. The targetportion 108 can be removably attached to the contact portion 107. Thetarget portion 108 and the contact portion 107 can couple via anymechanical connection such as a snap-fit, one or more hooks, pinch tabor button, slide pin, bayonet, and/or one or more magnets.

In some methods, the incise drape 109 is removed from a protectivecovering to expose an adhesive. In some methods, the surgeon can couplethe contact portion 107 with the incise drape 109. In some methods, theincise drape 109 and the contact portion 107 are provide to the surgeoncoupled. The surgeon can position the contact portion 107 relative tothe anatomy. The contact portion 107 can be positioned such that thecontact portion 107 is aligned with the optical component 174, 184. Thecontact portion 107 can be positioned against a portion of the anatomywith little or no soft tissue. The contact portion 107 can be positionedadjacent to the bone. In some embodiments, the contact portion 107contacts the skin of the patient. In some embodiments, the contactportion 107 is spaced from the skin of the patient

In some methods, the incise drape 109 can be coupled to the contactportion 107 prior to positioning the contact portion 107. In somemethods, the incise drape 109 can provide an adhesive to couple thecontact portion 107 to the patient. In some methods, the surgeonpositions both the contact portion 107 and the incise drape 109simultaneously. In some methods, the incise drape 109 can be coupled tothe contact portion 107 after to positioning the contact portion 107 onthe leg of the patient. In some methods, the incise drape 109 can becoupled to the patient after positioning the contact portion 107. Insome methods, the surgeon positions the contact portion and the incisedrape 109 independently. The surgeon can cover the anatomy with theincise drape 109. In some methods, the surgeon can wrap the anatomy withthe incise drape 109 forming one or more closed loops around theanatomy.

In some methods, the target portion 108 can be coupled to the contactportion 107 prior to positioning the contact portion 107. In somemethods, the target portion 108 can be coupled to the contact portion107 after to positioning the contact portion 107. In some methods, thetarget portion 108 can be coupled to the contact portion 107 by a snapfit connection. In some methods, the incise drape 109 is positioned overthe contact portion 107. In some methods, the target portion 108 cancouple to the contact portion 107 even if the incise drape 109 ispositioned over the contact portion 107. The target portion 108 cancouple to the contact portion 107 to form a rigid connection. The targetportion 108 can couple to the contact portion 107 to form a releasableconnection. In some embodiments, the target portion 108 cannot beremoved from the contact portion 107 once coupled.

The surgeon can activate the optical component 174, 194 to projectlight. The surgeon can align the optical component 174, 194 to project apattern of light on the target portion 108. One example of the incidenceof light is shown as 180. In some embodiments, the pattern of lightincludes two lines. In some embodiments, the pattern of light includestwo intersecting lines. The surgeon can adjust the optical component174, 194 such that the incidence of light 180 is located on the targetportion 108. In some embodiments, the optical component 174, 194 emitslight before or as the surgeon positions one or more of the contactportion 107, the target portion 108, and/or the incise drape 109. Insome embodiments, the optical component 174, 194 emits light after thesurgeon positions one or more of the contact portion 107, the targetportion 108, and/or the incise drape 109. The surgeon can mark theincidence of light 180 on the target portion 108. The target portion 108can include a markable, flat surface to facilitate the marking of theincidence of light 180. The surgeon can perform one or more methods ormethod steps described herein.

The surgeon can activate the optical component 174, 194 to project lightagain. The surgeon can move the anatomy of the patient connected to thetarget probe 18 e. In some methods, the target probe 18 e is coupled tothe thigh and the surgeon moves the thigh. In some methods, the targetprobe 18 e is coupled to the upper leg (e.g., femur) and the surgeonmoves the upper leg (e.g., femur). In some methods, the target probe 18e is coupled to the lower leg (e.g., tibia) and the surgeon moves thelower leg (e.g., tibia). In some methods, the target probe 18 e iscoupled to the foot and the surgeon moves the foot. The surgeon canrealign a portion of the anatomy such that the incidence of light 180aligns with the mark on the target portion 108. The surgeon can manuallyrealign a portion of the anatomy with the position of the anatomy whenthe incidence of light 180 was recorded. The surgeon can realign aportion of the anatomy in order to measure joint offset. The surgeon canrealign a portion of the anatomy in order to measure changes in leglength. The surgeon can realign a portion of the anatomy in order tocompare a measurement before and after joint replacement.

The surgeon can register a parked configuration or home position. Insome techniques, the distal end 780 of the probe 778 can be engaged witha point on the fixation base 702, such as the divot 730. The probe 778can be vertical in the home position. The orientation sensing device 204can be vertical in the home position. The distal end of the probe 778can be curved or bent to facilitate registering the home position.

When registering the home position, the user can hold the probe 778close to the distal end 780 to maximize accuracy of the measurement ofthe point. When interacting with the surgical orientation device 172,the user can support the back of the surgical orientation device 172 toavoid flexing the fixation pins 710, 712 and/or the fixation base 702.The user can register the home position by pressing a button of thesurgical orientation device 172. If the registration is not accepted,the user can keep the probe 778 stationary and press the button again.

FIG. 16 illustrates one embodiment of registering the table. FIG. 16 isa top view with the patient in the lateral decubitus position of theposterior approach. The surgeon can verify the sagittal plane of pelvisis level. During positioning of the patient, the Anterior Pelvic Planeis positioned vertically. The Anterior Pelvic Plane can be defined as aplane created by the two anterior superior iliac spines (ASIS) and theanterior surface of the pubic symphysis.

The Anterior Pelvic Plane can be oriented vertically when the patient isin the lateral decubitus position of the posterior approach. The topsurface of the operating table upon which the patient is positioned ispositioned horizontally. The patient can be positioned so that theAnterior Pelvic Plane is perpendicular to the table. In someembodiments, the surgeon can visually verify the Anterior Pelvic Planeis vertical. In some embodiments, the surgeon can use devices toposition the patient's body to align the Anterior Pelvic Planeperpendicular to the plane of the top surface of the table.

If not already horizontal, the surgeon can position operating tablehorizontally. The table plane can be a horizontal or generallyhorizontal plane. In some techniques, the operating table is horizontaland the table plane approximates the plane of the table. In sometechniques, the table plane can be oriented relative to other surface inthe operating room. In some techniques, the floor is horizontal and thetable plane approximates the plane of the floor. In some techniques, thewall is vertical and the table plane approximately a plane perpendicularto the wall. In some techniques, the ceiling is horizontal and the tableplane approximates the ceiling. Other surfaces may be use to approximatea horizontal plane.

During table registration, the probe 778 is coupled with the orientationsensing device 204. In some methods of use, the probe 778 and theorientation sensing device 204 are constrained. As one example, theprobe 778 can be coupled with other components of the first assembly 704and/or the second assembly 706. In some methods of use, the system 700is assembled, such that the first assembly 704 and the second assembly706 are coupled to the patient via the fixation pins 710, 712. There maybe mechanical constraints imposed by the configuration of the system700.

FIG. 16 illustrates one position of the probe 778 to calculate thedirection of gravity when the probe 778 is generally horizontal. Theprobe 778 is rotated and/or pivoted by the mount 758. The probe 778 canbe extended toward the patient's foot. The probe 778 can be aligned withthe long axis of the body. The probe 778 can be held substantiallyparallel to the plane of the table. In some embodiments, the user canalign the probe 778 with the horizontal. The user can visually inspectthe probe 778 from one or more locations. For instance, the user caninspect the probe 778 from a top view and a side view. In someembodiments, the user can align the probe 778 with the sagittal plane.The probe 778 can be parallel with the sagittal plane or a para-sagittalplane. The sagittal plane divides the body into right and left parts. Asdescribed herein, the orientation sensing device 204 can be positionedhorizontally to measure gravity. As described herein, the probe 778coupled to the orientation sensing device 204 can be positionedhorizontally or substantially horizontally to measure gravity. Referringback to FIG. 11, the side view of the patient illustrates one dashedline which is parallel to the table. During table registration, theprobe 778 can be parallel to the table as viewed from the side.

The probe 778 can be held in position or immobilized. The probe 778 canbe held steady during table registration. The second assembly 706 caninclude the lock 766. The lock 766 can limit or reduce slidablility ofthe probe 778 relative to the dock 762. In some methods of use, theprobe 778 can still pivot (e.g., pivotal motion between the dock 762 andthe mount 758). In some methods of use, the probe 778 can still rotate(e.g., rotational motion between the mount 758 and the probe bracket752). The lock 766 can reduce slidability when the table is registered.The lock 766 limits or reduces one degree of freedom during tableregistration.

The position and/or orientation of the orientation sensing device 204can be recorded by the surgical orientation device 172. The user canenter an input to register the table (e.g., depress a button on thesurgical orientation device 172). The user can interact with a userinterface on the surgical orientation device 172 to signal to thesurgical orientation device 172 to capture data of the orientationsensing device 204. The surgical orientation device 172 can indicatethat data was recorded. In some methods of use, the table registrationcan be taken at any point during the procedure. The table registrationcan be taken during pre-operative calibration. The table registrationcan be taken during intra-operative calibration. The table referenceframe can be calculated in addition or as an alternative to the tableplane. The surgical orientation device 172 can store the table planeand/or the table reference frame.

In some techniques, the table registration can be completed prior todislocating the hip. The torque applied during dislocation can movepelvis away from the correct initial alignment. In some techniques, thefixation base 702 cannot be adjusted by the user after tableregistration. For instance, the user cannot adjust the fixation base 702relative to the pins 710, 712. The fixation base 702 remains in positionfor the rest of the procedure. In some techniques, the pelvic bracket738 cannot be adjusted by the user after table registration. The pelvicbracket 738 remains in position for the rest of the procedure. In sometechniques, angle of the pelvic bracket 738 relative to the fixationbase 702 cannot be changed after table registration.

In some embodiments, information from one or more inertial sensors isused during table registration. As described herein, the orientationsensing device 204 and the surgical orientation device 172 can includeone or more inertial sensors. In some embodiments, the position and/orthe orientation of one or more inertial sensors can provide data relatedto the table plane. The one or more inertial sensors can detect gravityand provide a vector for the down direction.

The table registration can utilize a measurement of gravity. Asdescribed herein surgical orientation device 172 comprise one or moreinertial sensors. As described herein orientation sensing device 204comprise one or more inertial sensors. In some embodiments, inertialdata from one or more inertial sensors is used to calculate the verticalplane and/or horizontal plane. In some embodiments, the position and/orthe orientation data of one or more inertial sensors is used tocalculate the table plane or table reference frame. The surgicalorientation device 172 and/or the orientation sensing device 204 cancomprise an accelerometer, which can provide a measurement of thedirection of gravity. In some embodiments, the surgical orientationdevice 172 and/or the orientation sensing device 204 includes a sensorto detect the direction of gravity. The surgical orientation device 172and/or the orientation sensing device 204 can be sensitive to thedirection of gravity. The one or more inertial sensors can provide avector aligned with vertical, e.g., for the down direction. In someembodiments, the surgical orientation device 172 and/or the orientationsensing device 204 includes a three axis accelerometer to detectorientation relative to or of gravity.

In some embodiments, the surgical orientation device 172 includes anaccelerometer. In some embodiments, the orientation sensing device 204includes an accelerometer. The accelerometer at rest can measure theacceleration due to Earth's gravity. The accelerometer can measure theacceleration from gravity straight downward or vertically. In someembodiments, the accelerometer can detect the magnitude and direction ofthe force of gravity. The accelerometer can produce a vertical vector.The accelerometer can produce a horizontal vector by transforming thevertical vector (e.g., by rotation of 90 degrees). The accelerometer canprovide orientation and/or position data such that the table plane isperpendicular to the force of gravity.

In some embodiments, the orientation sensing device 204 measuresgravity. In some embodiments, the surgical orientation device 172measures gravity. The surgical orientation device 172 and/or theorientation sensing device 204 can provide an indication of theupward/downwards or vertical direction. The orientation sensing device204 and/or the surgical orientation device 172 can produce a verticalvector. The surgical orientation device 172 and/or the orientationsensing device 204 can produce a horizontal vector by transforming thevertical vector of gravity (e.g., by rotation of 90 degrees). In someembodiments, the surgical orientation device 172 remains stationary whenmeasuring gravity. In some embodiments, the surgical orientation device172 is coupled or affixed to the pelvis of the patient when measuringgravity. In some methods of use, the surgical orientation device 172 iscoupled to the patient via the fixation pins 710, 712 when measuringgravity. In some methods of use, the surgical orientation device 172 isconstrained when measuring gravity. As one example, the surgicalorientation device 172 can be coupled with other components of the firstassembly 704 and/or the second assembly 706. In some methods of use, theorientation sensing device 204 is constrained when measuring gravity. Asone example, the orientation sensing device 204 can be coupled withother components of the first assembly 704 and/or the second assembly706. In some embodiments, the orientation sensing device 204 and thesurgical orientation device 172 both determine the direction of gravity.In some embodiments, inertial data from two or more sensors are used tomeasure gravity.

The surgical orientation device 172 and/or the orientation sensingdevice 204 can provide a reference to gravitational zero. Gravitationalzero, as referred to herein, refers generally to an orientation in whichan axis of a sensor is perpendicular to the force of gravity, andthereby experiences no angular offset, for example tilt, pitch, roll, oryaw, relative to a gravitational force vector. The surgical orientationdevice 172 can store gravitational zero for calculations related to thetable plane. In some methods, gravitational zero is registered only onceand utilized throughout the procedure. The table registration caninclude recording a measurement of gravitational zero.

In some methods of use, the orientation sensing device 204 can bepositioned in other ways than horizontally to measure the direction ofgravity. In some methods of use, the orientation sensing device 204 canmeasure gravity when in the home position. In some methods of use, theorientation sensing device 204 can be positioned vertically orsubstantially vertically to measure gravity. In some methods of use, theorientation sensing device 204 can measure gravity when contacting apoint or anatomical landmark. In some methods of use, the orientationsensing device 204 can measure gravity when contacting the point beforecup placement. In some methods of use, the orientation sensing device204 can measure gravity when contacting the tracker 784. In some methodsof use, the orientation sensing device 204 can measure gravity whencontacting the point on the femur. The point on the femur can be a mark,such as Fm described herein. The point on the femur can be an anatomicallandmark. In some methods of use, the orientation sensing device 204 canmeasure the force of gravity at any angular orientation. In some methodsof use, the orientation sensing device 204 determine a vertical vectorof gravity when held at any position.

The table reference frame can include two perpendicular planes. The twoperpendicular planes can include a vertical plane and a horizontalplane. The table registration generates two planes, a plane including avector for the force of gravity and a plane perpendicular to said plane.The table plane is considered a horizontal plane. In some methods ofuse, the vector for the down direction can be used by the system toverify that the table plane is a horizontal plane. Plane. The horizontalplane may be recorded and stored by the surgical orientation device 172and/or the orientation sensing device 204.

In some methods of use, the vector for the down direction can be used bythe system to establish a vertical plane. In some methods of use, thevector for the down direction can be used by the system to establishtrue vertical and true horizontal. The vertical plane can approximatethe Anterior Pelvic Plane. For instance, abduction and anteversionangles can be calculated relative to the vertical plane. The verticalplane provides an estimation of the orientation of the Anterior PelvicPlane. The vertical plane may be recorded and stored by the surgicalorientation device 172 and/or the orientation sensing device 204. Thesystem 700 can calculate cup angles based on the vertical plane based onthe assumption that the pelvis of the patient is correctly positionedsuch that the Anterior Pelvic Plane is vertical. In some methods of use,the abduction and anteversion angles in cup placement in total hiparthroplasty can be with respect to the vertical plane determined duringtable registration.

The orientation of the vertical plane can be a baseline for placement ofthe cup portion of a hip prosthesis. The surgical orientation device 172can display information with respect to the vertical plane. In somemethods of use, the abduction and anteversion angles in cup placement intotal hip arthroplasty can be with respect to the vertical plane. Insome embodiments, the vertical plane is determined by the surgicalorientation device 172 and/or the orientation sensing device 204. Insome embodiments, the surgical orientation device 172 and/or theorientation sensing device 204 can provide orientation and/or positiondata related to the table reference frame. In some embodiments, thesurgical orientation device 172 and/or the orientation sensing device204 can provide orientation and/or position data related to verticalplane. In some embodiments, the surgical orientation device 172 and/orthe orientation sensing device 204 can provide orientation and/orposition data related to horizontal plane.

In some embodiments, the table plane is determined completelyindependently of any anatomical landmarks. The table plane provides areference plane that is unaffected by pelvic tilt. The table planeprovides a reference plane that is unaffected by errors in landmarkregistration due to soft tissue. The table plane also appears in largeconsole navigation which might be familiar to the surgeon. In somemethods of use, the horizontal plane is calculated based on aligning theprobe 778. In some methods of use, the vertical plane is calculatedbased on a measurement of gravity. In some methods of use, target cupangles are relative to the Anterior Pelvic Plane. In some methods ofuse, navigated cup angles are relative to the vertical plane whichapproximates the Anterior Pelvic Plane. The pre-operative and/orpost-operative images, such as x-rays, are captured within a referenceplane similar to the Anterior Pelvic Plane. The table registration mayprovide a reference plane that approximates the reference plane ofimaging techniques. The table registration may provide a reference planethat approximates the Anterior Pelvic Plane.

Referring to FIGS. 17A-17B, in some methods of use, the surgeon canregister a point. In some methods of use, the surgeon can register onlyone point. In some methods of use, the surgeon registers a single pointon the femur. In some methods of use, the surgeon registers a singleanatomical landmark during the procedure. The point can be located onfemur of the joint being operated on. For some procedures on a patient'sleft hip, the point is on the left femur. For some procedures on apatient's right hip, the point is on the right femur. In some methods ofuse, the surgeon can make the standard incision. In some methods of use,the surgeon can identify a point along the transtrochanteric line on theproximal femur. In some methods of use, the point is the located on thegreater trochanter.

The surgeon can position the distal end 780 of the probe 778 at thepoint. In some methods of use, the distal end 780 of the probe 778 isplaced on the point on the greater trochanter. In some methods of use,the tip of the distal end 780 is brought into contact with a part of thegreater trochanter or elsewhere on the proximal femur. In some methodsof use, the tip of the distal end 780 is brought into contact with anypoint on the anatomy of the patient.

In some methods of use, after a point is found and/or contacted, theclinician can make a mark on the femur. In some methods of use, thesurgeon can make a mark using a bovie mark, a pen mark, a stitch orother durable indication. In some methods of use, the surgeon can coupletracker 784. The tracker 784 can be fastener such as a screw, bolt, pin,plate, or other durable structure. In some methods of use, the surgeoncan insert 20 mm screw into the femur. In some embodiments, the tracker784 can be secured to the femur. The tracker 784 can be rotated to besecured into the femur. The tracker 784 can be advanced into the femurwith a driver. The surgeon should ensure that the tracker 784 is lateralenough so as not to interfere with the stem. The point can be located onthe tracker 784. In some methods of use, the surgeon can make a divot orburr into a bone or other portion of the anatomy of the patient. In someembodiments, the divot or burr is in the femur. The point can be locatedon the divot or burr. In some methods of use, the surgeon can alter thefemur to provide a reliable indication of the point that is registered.

The probe 778 can be immobilized to register the point. In someembodiments, the surgeon can hold the tip of the probe 778 at the point.In some embodiments, the surgeon can hold the tip of the probe 778 in adivot or burr. In some embodiments, the surgeon can hold the tip of theprobe 778 in a hole of the tracker 784. In some embodiments, the surgeoncan hold the tip of the probe 778 at an anatomic landmark. In someembodiments, the surgeon can hold the tip of the probe 778 at the markedpoint Fm.

As described herein, the second assembly 706 can include a lock 766. Thelock can limit or reduce slidablility of the probe 778 relative to thedock 762. In some methods of use, the probe 778 can still pivot (e.g.,pivotal motion between the dock 762 and the mount 758). In some methodsof use, the probe 778 can still rotate (e.g., rotational motion betweenthe mount 758 and the probe bracket 752). The lock 766 can reduceslidability when the point is registered. In some embodiments, the lock766 is advanced before the point is registered. In some methods of use,the lock 766 limits or reduces one degree of freedom during pointregistration.

Once the tip of the distal end 780 is in contact with the desired point,the system 700 processes data from and stores the orientation of one ormore sensor(s) in the orientation sensing device 204. Duringregistration, the position of the orientation sensing device 204 can berecorded by the surgical orientation device 172. During registration,the orientation of the orientation sensing device 204 can be recorded bythe surgical orientation device 172. During registration, the extensionof the orientation sensing device 204 can be recorded by the surgicalorientation device 172.

The distance related to the extension of the probe 778 can be used inconjunction with the positional and/or orientation data from theorientation sensing device 204. Additionally, in some embodiments, theprobe 778 is provided with a marking 782 indicating position of the tipof the probe 778, e.g., relative to the dock 762 or some other relevantfixed feature of the patient or the system 700. The marking 782 can beread by the clinician or the camera 184. In some embodiments, the camera184 records the marking 782 indicating the extension of the probe 778.The distance that the probe 778 is extended, as captured by the camera184, to contact the point can be recorded by the orientation device 172.In some methods, the orientation sensing device 204 or the surgicalorientation device 172 can converts the image of the camera 184 into anextension measurement of the probe 778. When registering the anatomicalpoints, the camera 184 captures an image of the marking 782. The camera184 can read the marking 782 to provide accurate determination of thetranslational position of the probe 778 relative to the dock 762. Thecamera 184 can be directly above the marking 782. In some methods, thecamera 184 can read a binary code of the marking 782. The surgicalorientation device 172 can use the length measurement from the camera184 and the data from the orientation sensing device 204 to determinethe location of the distal end 780 of the probe 778.

In some embodiments, the surgeon will enter an input (e.g., depress abutton) to collect data from the orientation sensing device 204. In somemethods, the surgeon will enter an input (e.g., depress a button) tocollect data from the camera 184. In some embodiments, the surgeon willenter an input (e.g., depress a button) to collect data from theorientation sensing device 204 and the camera 184 simultaneously. Insome methods, the orientation sensing device 204 and/or the camera 184will only send data if the orientation sensing device 204 is stable ornon-moving. In some embodiments, the surgeon can press a button on thesurgical orientation device 172 to register the point. The surgeon canenter an input to register the point. Other ways of entering an inputinclude interacting with a touchscreen, using a verbal command, touchingan icon, holding the probe 778 steady for a period of time, and/orreaching the end of a countdown clock, etc. The surgical orientationdevice 172 can indicate that the point was recorded.

In some methods, the surgeon marks the incidence of light beforeregistering the point. In some methods, the surgeon marks the incidenceof light after registering the point. In some methods, the surgeon marksthe incidence of light simultaneously with registering the point. Insome methods, the surgeon marks the incidence of light but does notregister the point. In some methods, the surgeon registers the point butdoes not mark the incidence of light. In some methods, the surgeon marksthe incidence of light independently of registering the point. In somemethods, the surgeon marks the incidence of light and registers thepoint after the leg is secured. In some methods, the surgeon marks theincidence of light and registers the point when the leg is in the sameorientation.

The surgical orientation device 172 can record a point in the tablereference frame. The table reference frame can form a coordinate system.The table reference frame can include the vertical plane and thehorizontal plane. In some methods of use, the registered point islocated at the origin of the table reference frame. In some methods ofuse, the center of rotation of the femur is located at the origin of thetable reference frame. The user can record a point in the tablereference frame before cup placement. The user can record the same pointin the table reference frame after cup placement. The system 700 cancompare the measurement of the same point before and after cupplacement. The comparison can relate to leg length. The comparison canrelate to joint offset. In some embodiments, changes in the registeredpoint along the vertical plane indicate a change in leg length. In someembodiments, changes in the registered point along the horizontal planeindicate a change in joint offset.

In some techniques, the table registration is completed prior todislocating the hip. In some techniques, the point is registered priorto dislocating the hip. In some techniques, the incidence of light ismarked prior to dislocating the hip. Once registration is complete, thesurgeon can proceed to dislocate the hip, resect the femoral head, andprepare the acetabulum as per the implant manufacturer's technique. Thetorque applied during dislocation can move pelvis away from the correctinitial alignment.

In some techniques, the fixation base 702 cannot be adjusted by the userafter table registration, home registration, recording the incidence oflight, and/or point registration. For instance, the user cannot adjustthe fixation base 702 relative to the pins 710, 712. The fixation base702 remains in position for the rest of the procedure. In sometechniques, the pelvic bracket 738 cannot be adjusted or removed. Thepelvic bracket 738 remains in position for the rest of the procedure. Insome techniques, angle of the pelvic bracket 738 relative to thefixation base 702 cannot be changed. In some techniques, the probe 778cannot be replaced with a different probe. The same probe 778 is usedfor the remainder of the procedure.

In some methods of use, the surgical orientation device 172 can provideoptions to the user regarding how to proceed. In some methods of use,the surgeon can set anteversion and/or abduction cup angles. In somemethods of use, the surgical orientation device 172 can store target cupangles. In some methods of use, the surgeon can input anteversion and/orabduction cup angles into the surgical orientation device 172. In somemethods of use, the surgeon set the target angle of the cup. In somemethods of use, the surgical orientation device 172 can allow thesurgeon to check the target angles after the surgeon sets the targetangle of the cup.

In some methods of use, the surgical orientation device 172 can provideoptions related to leg length and joint offset. In some methods of use,the surgical orientation device 172 can measure leg length from apre-operative state. In some methods of use, the surgical orientationdevice 172 can measure offset from a pre-operative state. In somemethods of use, the surgical orientation device 172 can measure leglength before cup placement. In some methods of use, the surgicalorientation device 172 can measure joint offset before cup placement. Insome methods of use, the surgical orientation device 172 can measurechanges in the registered point. In some methods of use, the surgicalorientation device 172 can measure changes in the registered point inthe table reference frame. In some methods of use, the surgicalorientation device 172 can measure changes in the registered point inthe table reference frame comprising the vertical plane. In some methodsof use, the surgical orientation device 172 can measure changes in theregistered point in the table reference frame comprising the horizontalplane. In some methods of use, the surgical orientation device 172 canmeasure changes in the registered point in the table reference framecomprising the vertical plane and the horizontal plane.

In some methods of use, the surgical orientation device 172 can provideoptions related to the home position. In some methods of use, thesurgeon can position the probe 778 at the home position during theprocedure. In some methods of use, the surgeon can position the probe778 at the home position to verify that one or more components of thesystem 700 remain fixed. In some methods of use, the surgicalorientation device 172 can repeat the registration of a point. In somemethods of use, the surgical orientation device 172 can repeat theacquisition of the point used. The surgical orientation device 172 canrepeat acquisition of the point before the joint is dislocated. Thesurgical orientation device 172 can repeat acquisition of the pointafter insertion of a medical prosthesis. In some methods of use, thesurgical orientation device 172 can indicate the end of the procedure.In some methods of use, the surgeon can end the procedure to select theother hip for a bi-lateral procedure.

Once registration is complete, the user can proceed to proceed todislocate the hip, resect the femoral head, and prepare the acetabulum.The user can prepare the impactor and shell. The user can remove thesecond assembly 706 from the first assembly 704. The user can remove theorientation sensing device 204 from the probe 778. The user can dock theorientation sensing device 204 to the first assembly 704. The surgicalorientation device 172 and the orientation sensing device 204 form ageneral V-shaped configuration, similar to the orientation shown in FIG.12. The user can set the cup angle. In some methods of use, the surgeoncan hold the hip stable until the surgical orientation device 172provides an indication to proceed.

The user can remove the orientation sensing device 204 from the firstassembly 704. The orientation sensing device 204 and the surgicalorientation device 172 can at this point be used to guide placement ofthe cup in the prescribed orientation. The surgeon can remove theextension 770 from the third coupler 768. The surgeon can couple theextension 770 to an impactor. In some embodiments, if the orientationsensing device 204 is moved too quickly, an error message will appear onthe surgical orientation device 172. In some embodiments, if theorientation sensing device 204 is moved too quickly, the orientationsensing device 204 can be coupled to the first assembly 704 as shown inFIG. 12.

FIG. 18A illustrates an embodiment of an impactor 300A. In some methodsof use, the orientation sensing device 204 can be coupled to theimpactor 300A. The orientation sensing device 204 can determine cupangles relative to a reference plane as the impactor 300A is moved. Theimpactor 300A can include a shell 312A. The movement of the shell 312Ais cushioned by a plurality of spring members 340, 344 which areconfigured to absorb at least some of the shock of the impact on theimpactor 300A. The shell 312A can include a fourth coupler 342 (seeFIGS. 18B-18D). This fourth coupler 342 permits the orientation sensingdevice 204 to couple to the shell 312A. The orientation sensing device204 can be removably coupled to the fourth coupler 342. The orientationsensing device 204 can be coupled to the impactor 300A in order tonavigate cup angles, as described herein.

In some embodiments, the fourth coupler 342 can be a universal coupler.This permits the fourth coupler 342 couple to any other device orsubsystem, as described herein. In some embodiments, the fourth coupler342 is identical or substantially similar to the first coupler 632,second coupler 648, and/or the third coupler 668. The fourth coupler 342can couple to one or more components of the system 600, such as theorientation sensing device 204. The fourth coupler 342 can include anelongate post. The fourth coupler 342 can include a slot. The slot canbe designed to lock with the orientation sensing device 204, or acomponent thereof such as the extension 670. The extension 670 caninclude a detent. The detent can be sized and shaped to be receivedwithin the slot of the fourth coupler 342. The engagement of the detentand the slot can rigidly couple the orientation sensing device 204 withthe fourth coupler 342. The engagement between the fourth coupler 342and the extension 670 of the orientation sensing device 204 minimizes orprevents relative movement therebetween to avoid any mechanical relativemovement during navigation procedures.

The fourth coupler 342 can include a tapered surface. The taperedsurface can facilitate entry of the fourth coupler 342 into theextension 670. In some embodiments, the fourth coupler 342 can have aregular shape (e.g., cylindrical). In some, the orientation sensingdevice 204 can mate with the fourth coupler 342 in a plurality oforientations. In some embodiments, the fourth coupler 342 can have anirregular shape (e.g., triangular, teardrop, elliptical, rectangular).The irregular shape can facilitate alignment of the orientation sensingdevice 204 relative to the fourth coupler. In some, the orientationsensing device 204 can mate with the fourth coupler 342 in a singleorientation.

The orientation sensing device 204 can be releasbly coupled to theextension 670. The extension 670 can include a mount 672 designed tocouple with the orientation sensing device 204. In the illustratedembodiment, the mount 672 includes a lock and release lever that canpivot relative to the extension 670. The orientation sensing device 204can include features to mate with the lock and release lever. Otherconfigurations are contemplated. The orientation sensing device 204 isrigidly coupled to the extension 670 when engaged by the mount 672.

In some embodiments, impactor 300A is provided which includes the shell312A with the fourth coupler 342. The impactor 300A can be provided bythe manufacturer of other components of the systems described herein.The impactor 300A can include the forth coupler 342 to allow theimpactor 300A to interface with the orientation sensing device 204. Insome embodiments, an impactor is provided which does not include thefourth coupler 342. FIGS. 18B-18D illustrate embodiments of a universalimpactor adapter. The universal impactor adapter can allow any impactorto be used with the systems described herein. The universal impactoradapter can allow the orientation sensing device 204 to couple with anyimpactor. In some embodiments, the universal impactor adapter can be anattachment which provides the fourth coupler 342 to allow theorientation sensing device 204 to mount thereon. The orientation sensingdevice 204 can mount on a large array of impactors, not only impactor300A. The universal impactor adapter can be coupled to any impactor toprovide the fourth coupler 342. The universal impactor adapter canprovide a means to rigidly couple the fourth coupler 342 to theimpactor. The universal impactor adapter can provide a means to rigidlycouple the orientation sensing device 204 to the impactor.

FIG. 18B is an embodiment of a universal impactor adapter 350. FIGS.18C-18D is an embodiment of a universal impactor adapter 352. Theuniversal impactor adapter 350, 352 can be designed to couple to aplurality of impactors. The universal impactor adapter 350, 352 can bedesigned to couple to impactors having a certain range of sizes ofshafts or coupling portions. The universal impactor adapter 350, 352 canbe designed to couple to impactors having a different shapes orconfigurations. The universal impactor adapter 350, 352 can include thefourth coupler 342. The universal impactor adapter 350, 352 can includeany coupler designed to couple to the orientation sensing device 204.The universal impactor adapter 350, 352 can couple to a shaft of animpactor by any manner of connections. The universal impactor adapter350 can connect to a shaft of an impactor with one or more magnets 354.The one or more magnets 354 of the universal impactor adapter 350 can beconfigured to attract and couple to the one or more magnets (not shown)of an impactor. The impactor is configured to be inserted within therecess 358. The recess 354 is an arcuate channel for receiving a shaftof an impactor within a range of impactor shaft sizes. While fourmagnets 354 are shown in FIG. 18B, other configurations are contemplated(e.g., one magnet, two magnets, three magnets, four magnets, fivemagnets, six magnets, etc.). The four magnets can be angled downwardtoward the recess 358. This orientation is to concentrate the magneticforce in the recess 358 to enhance the attraction of the adaptor 350 toa shaft of an impactor that is fitted in the recess 358. The fourmagnets can be angled downward relative to the fourth coupler 342. Whiletwo magnets are shown on one side of the universal impactor adapter 350,two additional magnets 354 have a mirror image configuration on theother side of the device in the illustrated embodiment. The magnets aredirected toward the recess 358 are configured to interact withcorresponding magnets of the impactor in one embodiment. The one or moremagnets 354 of universal impactor adapter 350 can be configured toattract and couple to the one or more magnets of the impactor. In someembodiments, one or more magnets 354 can be configured to attract amagnetic material disposed on or in the shaft of the impactor. In someembodiments, the impactor, or a portion thereof, comprises a magneticmaterial. In some embodiments, the entire impactor is magnetic. The oneor more magnets 354 of the universal impactor adapter 350 can allow theuniversal impactor adapter 350 and the forth coupler 342 to form aself-supporting structure with the impactor when assembled. The forthcoupler 342 can be rigidly coupled such that any movement of theimpactor causes correcting movement of the fourth coupler and thereference sensor device 204 coupled thereto. The one or more magnets 354of the universal impactor adapter 350 can reduce or prevent unwantedmovement between the impactor and the orientation sensing device 204.

The universal impactor adapter 352 can connect to a shaft of an impactorwith one or more clamps 356. FIG. 18C illustrates the clamp 356 whentightened and FIG. 18D illustrates the clamp 356 when loosened. Theclamp is an example of a mechanical connection between the universalimpactor adapter 352 and any impactor. The clamp 356 can include a roundinner surface to connect to a round outer surface an impactor.

The clamp 356 of the universal impactor adapter 352 can allow theuniversal impactor adapter 352 and the forth coupler 342 to formself-supporting structure with the impactor. The clamp 356 of theuniversal impactor adapter 352 can reduce or prevent unwanted movementbetween the impactor and the orientation sensing device 204. The clamp356 can apply a force necessary to rigidly couple to the exteriorsurface of the impactor. Other configurations of the universal impactoradapter are contemplated.

The impactor 300A or any impactor with the universal impactor adapter350, 352 can be modified to suit any of a plurality of hip prostheses.For example, a plurality of tip components 348 can be provided in a kitwhere each tip component is attachable to and detachable from a distalend of the shaft of the impactor. Two types of tip adapters are shown inFIG. 12C. In some embodiments, the tip adapter 348 can be offset. Theplurality of tip adaptors is optional.

The acetabular shell can be threaded onto a tip component 348. The usercan select the appropriate shell adapter for the desired impactor. Theimpactor 300A or any impactor with the universal impactor adapter 350,352 also is configured to be modified to suit any of a plurality of hipprostheses. In some methods of use, the surgeon can thread acetabularshell onto tip component 348. In some methods of use, the surgeon cansnap the tip component 348 onto end of impactor shaft. In someembodiments, the tip component 348 can be rotated to multiple anglesrelative to impactor to align the screw holes of shell as desired. Insome embodiments, if none of available tip component 348 fit on selectedshell, then the impactor 300A cannot be navigated. In some embodiments,if none of available tip component 348 fit on selected shell, thenanother impactor is selected based on the selected shell. The impactorcan be outfitted with the universal impactor adapter 350, 352 to be ableto couple with the orientation sensing device 204. In some embodiments,prior to impacting, the surgeon can verify shell is fully seated onshoulder of impactor. In some embodiments, prior to impacting, thesurgeon can verify that threads do not protrude beyond outer face ofshell. Another embodiment of an impactor is shown in FIG. 12C. Theimpactor 300B can have any of the features of the impactor 300Adescribed herein. The impactor 300B is an offset shell impactor. Theimpactor 300A is a straight shell impactor. The plurality of impactorsis optional.

In some methods of use, the impactor is not navigated as describedherein. In some embodiments, the cup angle can be checked afterinsertion by registering the hip center. In some methods of use, thesurgeon can register three points on the outer rim of the cup. Thesethree points define the hip center. In some embodiments, the point whichis equidistant from all three points is the hip center. Additionally,these three points define the plane of the cup. The cup angle is definedas the angle of an axis which is perpendicular to this plane. Note thatthe impactor is perpendicular to this axis. Additional informationregarding the registration of points and identification of the hipcenter can be found in U.S. application Ser. No. 14/639,758 filed Mar.5, 2015; Ser. No. 14/639,784 filed Mar. 5, 2015; Ser. No. 13/800,620,filed Mar. 13, 2013; and Ser. No. 14/643,864 filed Mar. 10, 2015, thedisclosures of which are incorporated by reference in their entirety. Insome methods of use, there is no registration of the hip center. In somemethods of use, only a single point is registered. In some methods ofuse, the point is registered before and after cup placement for leglength and/or joint offset. In some methods of use, no points areregistered. In some methods of use, the surgeon does not calculate leglength and/or joint offset using point registration.

The acetabular shell can be inserted into the acetabulum and positionedat the desired angle. As described herein, the surgeon can store targetangles with the surgical orientation device 172. The surgicalorientation device 172 can guide the surgeon in placing the cup relativeto the target angles. As described herein, the target abduction andanteversion angles can be cup angles entered by the surgeon into thesurgical orientation device 172. The target abduction and anteversionangles can be an input into the system 700.

In some methods of use, once the orientation sensing device 204 isattached to impactor 300A or any other impactor with the universalimpactor adapter 350, 352, the surgical orientation device 172 candisplay radiographic inclination and anteversion angles of impactor. Insome methods of use, once the orientation sensing device 204 is attachedto impactor, the surgical orientation device 172 can displayradiographic inclination and anteversion angles of impactor relative tofrontal pelvic plane. In some methods of use, once the orientationsensing device 204 is attached to impactor, the surgical orientationdevice 172 can display radiographic inclination and anteversion anglesof impactor relative to the vertical plane. In some methods of use, oncethe orientation sensing device 204 is attached to impactor, the surgicalorientation device 172 can display radiographic inclination andanteversion angles of impactor relative to a plane that approximates theAnterior Pelvic Plane. The angle of the impactor can be calculated inreal-time.

The surgical orientation device 172 can graphically display when theorientation sensing device 204 is navigated to the target abduction andanteversion angles. The surgical orientation device 172 can includeindicia such as a target or bullseye to indicate the pre-determinedabduction and anteversion angles. The surgical orientation device 172can include indicia such as a dot or cross-hair to indicate movement ofthe impactor. Aligning the indicia in the center of the target orbullseye can indicate that the impactor is aligned with thepredetermined cup angles. In some methods of use, the surgeon alignscross-hairs in a center of a bull's eye. In some methods of use, thesurgeon aligns a bubble level. In some methods of use, the surgeonaligns two indicia. In some methods of use, the surgeon substantiallyaligns a moving indicia with a fixed indicia. In some methods of use,the surgeon moves an indicia on the user interface of the surgicalorientation device 172 by moving the impactor. In some methods of use,the surgeon moves an indicia on the user interface of the surgicalorientation device 172 by moving the orientation sensing device 204.Aligning a visual indicator displayed on the surgical orientation device172 can guide the user to position the impactor at the desired cupangles. The indicia can move in real-time.

The surgical orientation device 172 can graphically display theabduction and anteversion angles as the orientation sensing device 204is moved. In some methods of use, the indicia align when the impactor ispositioned at the target anteversion angle. In some methods of use, theindicia align when the impactor is positioned at the target abductionangle. In some methods of use, the surgeon enters the target anteversionangle and/or the target abduction angle into the surgical orientationdevice 172.

In some methods of use, the surgical orientation device 172 displays atarget angle. The target abduction and anteversion angles can bedisplayed statically. The surgical orientation device 172 can include areadout of the abduction and anteversion angles. The readout of theabduction and anteversion angles can change as the impactor is moved.The readout of the abduction and anteversion angles can be in real-time.In some methods of use, the surgeon compares readout and the targetangle to position a cup at the target angle. In some methods of use, thesurgical orientation device 172 provides a graphical display to assistthe surgeon in aligning the cup with the target angles. In some methodsof use, the surgical orientation device 172 provides a user interface toassist the surgeon in aligning the cup with the target angles. In somemethods of use, the surgical orientation device 172 provides visualfeedback when the impactor is aligned with one or more target angles. Asdescribed herein, angles displayed can be calculated according to theirradiographic definitions. In some methods of use, the surgicalorientation device 172 can provide the readout of angles dynamically.

The user can enter an input once the desired cup angles are reached. Theuser can have a set amount of time to align the impactor with thedesired cup angles. In some methods of use, the surgeon must align theimpactor at the desired target angle within a period of time. In somemethods of use, the surgeon must align the impactor at the desiredtarget angle within 30 seconds, 25 second, 20 seconds, less than aminute, less than 30 seconds, etc. The user can align impactor atdesired cup angle. In some methods, after the impactor is positionedrelative to the desired cup angles, the cup angles can be displayedstatically. The cup angles can be checked after impacting by repeatingone or more of the proceeding steps.

In some methods of use, the surgical orientation device 172 proceeds tothe next step if the timer expires (e.g., 30 second timer, 25 secondtimer, 20 second timer, 1 minute timer, etc.). In some methods of use,the surgical orientation device 172 proceeds to the next step if abutton of the surgical orientation device 172 is pressed. In somemethods of use, the surgical orientation device 172 proceeds to the nextstep if the orientation sensing device 204 detects an impact strongenough to disrupt navigation. In some methods of use, the surgicalorientation device 172 displays abduction and/or anteversion cup anglesstatically. In some methods of use, the surgical orientation device 172displays abduction and/or anteversion cup angles statically afterimpaction. In some methods of use, the surgical orientation device 172displays abduction and/or anteversion cup angles after the timerexpires. In some methods of use, the surgical orientation device 172displays abduction and/or anteversion cup angles after the user entersan input, such as depressing a button. In some methods of use, thesurgical orientation device 172 displays abduction and/or anteversioncup angles after navigation has ended.

The surgical orientation device 172 can provide cup angles relative toany reference plane, including those described herein. The surgicalorientation device 172 can provide cup angles relative to the verticalplane. The surgical orientation device 172 can provide cup anglesrelative to a plane that approximates the Anterior Pelvic Plane. Thesurgical orientation device 172 can provide cup angles relative to aplane acquired during table registration. The surgical orientationdevice 172 can provide cup angles relative to a plane that includes avector for gravity.

In some embodiments, the surgeon can check cup angle after impacting ascup angle will change during impaction. In some embodiments, the cupangle is displayed up to the beginning of impaction, typically after thefirst mallet strike. In some methods of use, the surgeon will typicallystrike the impactor several times during cup placement. In some methodsof use, these strikes may change the orientation of the cup. In someembodiments, the surgical orientation device 172 displays only the cupangle from prior to impaction. In some methods of use, the surgeon willrepeat the cup navigation procedure by coupling the orientation sensingdevice 204 to the first assembly 704 such that it is in a fixedorientation with the surgical orientation device 172. In some methods ofuse, the configuration can be similar to the configuration shown in FIG.12A. In some methods of use, the surgeon can interact with theorientation sensing device 204 and/or surgical orientation device 172using one or more of the method steps described herein. Then the surgeonwill move the orientation sensing device 204 to the impactor. The system700 will now display the current cup angle. In some embodiments, thesurgeon can check cup angle after impacting to improve accuracy. In someembodiments, the surgeon can verify the position of orientation sensingdevice 204 and the surgical orientation device 172 after impactingbefore checking angles. In some embodiments, the surgeon can visuallyconfirm cup angles before proceeding.

After positioning the cup, the user can attach the second system 706 tothe first system 704, similar to the configuration shown in FIG. 7. Insome methods of use, the user can measure for leg length and/or jointoffset. At the surgeon's discretion, the system 700 can be used tonavigate a condition, location and/or orientation of the femur prior tohip replacement. At the surgeon's discretion, the system 700 can be usedto navigate a condition, location and/or orientation of the femur afterhip replacement.

Referring to FIG. 19A-19B, the surgeon can manually re-position thefemur. In some embodiments, the surgeon can manually re-position thefemur in the orientation in which the point was recorded. In someembodiments, the surgeon can manually re-position the femur in theorientation prior to cup placement. In some embodiments, the surgeon canmanually re-position the femur in the orientation prior to jointreplacement. In some methods, the surgeon opens the shutter of theoptical component 174, 194. The method can include projecting light fromthe optical component 174, 194. In some methods of use, the incidence oflight may not align with the marking. In some methods of use, the femurhas moved from the orientation when the point was registered. In somemethods of use, the femur has moved from a previously recordedorientation. In some methods, the surgeon positions the leg so that theoptical component 174, 194 projects a light onto the leg. In someembodiments, the optical component 174, 194 projects onto the femur. Insome embodiments, the optical component 174, 194 projects onto thesterile wrap. In some embodiments, the optical component 174, 194projects light onto the distal thigh.

Referring to FIGS. 19A-19B, the method can include aligning incidence oflight with the prior marking or recording of the incidence of the light.In some embodiments, the surgeon can manually position the femur bymoving the femur. The femur can be moved in anterior-posteriordirection. The femur can be moved in varus-vulgas direction. The femurcan be rotated about the head of the femur. In some embodiments, thesurgeon can manually position the femur after the joint is replaced,such as after a cup is placed within the joint. In some embodiments, thesurgeon can realign the femur such that the femur is in same positionbefore and after cup placement. In some embodiments, the surgeon canrealign the femur such that the femur is in same position before andafter joint replacement. In some embodiments, the surgeon can positionthe femur to be in the same position as when the surgeon traced theincidence of light. In some embodiments, the surgeon can position thefemur to be in the same position as when the surgeon recorded the point.The surgeon can extend and/or rotate the femur to position the femur.

In some embodiments, the surgeon positions the leg such that theincidence of light from the optical component 174, 194 aligns with thetraced pattern. In some embodiments, the surgeon positions the femurrelative to the pelvis. In some embodiments, the surgeon positions thefemur such that the incidence of light from the optical component 174,194 aligns with one or more marks. In some embodiments, the surgeonpositions the femur such that the incidence of light aligns with twolines. In some embodiments, the surgeon positions the femur such thatthe incidence of light aligns with a marked cross-hair. In someembodiments, the surgeon positions the femur such that the incidence oflight aligns with three marked points. In some embodiments, the surgeonpositions the femur such that the incidence of light aligns with amarking on the sterile wrap. In some embodiments, the surgeon positionsthe femur such that the incidence of light aligns with a marking on thetarget probe 18 a, 18 b. In some embodiments, the surgeon positions thefemur such that the incidence of light passes through one or more slotsof the target probe 18 a, 18 b. In some embodiments, the surgeondiscontinues use of the optical component if the cross-hair pattern isobscured.

Referring to FIG. 19C, in some methods of use, the surgeon can registerthe point after positioning the femur. In FIG. 19C, the incidence oflight 180 aligns with the marking. While a cross-hair pattern is shownin FIG. 19C, the incidence of light 180 and the marking can be anypattern. By aligning the incidence of light 180 and the marking, thefemur is in the same position before and after cup placement.

In some methods of use, the surgeon can register the point after cupplacement. In some methods of use, the surgeon can register the samepoint intra-operatively. In some embodiments, the surgeon can registerthe point after the cup is placed at one or more desired target angles.In some embodiments, the surgeon can register the point after jointreplacement. The surgeon can position the distal end 780 of the probe778 at the point. In some methods of use, the distal end 780 of theprobe 778 is placed on part of the greater trochanter or elsewhere onthe proximal femur. In some methods of use, the distal end 780 of theprobe 778 is placed on the mark on the femur. In some methods of use,the distal end 780 of the probe 778 is placed on the tracker 784. Insome methods of use, the distal end 780 of the probe 778 is placed on adivot or burr on the femur.

The probe 778 can be immobilized to register the point. In someembodiments, the surgeon can hold the tip of the probe 778 at the point.The second assembly 706 can include a lock 766. The lock 766 can limitor reduce slidablility of the probe 778 relative to the dock 762. Thelock 766 limits or reduces one degree of freedom during pointregistration.

Once the tip of the distal end 780 is in contact with the desired point,the system 700 processes data from and stores the orientation of one ormore sensor(s) in the orientation sensing device 204. Duringregistration, the position of the orientation sensing device 204 can berecorded by the surgical orientation device 172. During registration,the orientation of the orientation sensing device 204 can be recorded bythe surgical orientation device 172. During registration, the extensionof the orientation sensing device 204 can be recorded by the surgicalorientation device 172. In some embodiments, the surgical orientationdevice 172 can register the point. In some embodiments, the surgeon canpress a button on the surgical orientation device 172 to register thepoint.

In some methods, the surgeon aligns the marking with the projection oflight before registering the point. In some methods, the surgeon alignsthe marking with the projection of light simultaneously with registeringthe point. In some methods, the surgeon aligns the marking with theprojection of light but does not register the point. In some methods,the surgeon registers the point but does not align the marking with theprojection of light. In some methods, the surgeon aligns the markingwith the projection of light independently of registering the point. Insome methods, the surgeon aligns the marking with the projection oflight and registers the point after the leg is fixed. In some methods,the surgeon aligns the marking with the projection of light, secures thefemur, and then registers the point after the femur is secured.

If the point is acquired in the procedure prior to separating thenatural joint, the same point can be acquired after the prosthetic jointis placed to confirm that the replacement of the joint has not changedeither the length of the leg, the off-set of the leg from the trunk ofthe patient, or both. After joint replacement, the distal end 780 of theprobe 778 can be brought into contact with the same point acquired earlyin the procedure. The orientation of the orientation sensing device 204and the extension of the probe 778 can be input into the surgicalorientation device 172. These data enable the surgical orientationdevice 172 to output amounts of change in leg length and leg offset.

The system 700 can measure the orientation of the femur relative topelvis during a baseline measurement of the point. The system 700 canmeasure the orientation of the femur relative to pelvis during one ormore intra-operative measurements of the point. The system 700 can storethe two-dimensional coordinates of the point in the table referenceframe. In some methods of use, the surgeon can correct for changes inorientation by doing a rotation about the center of rotation of thefemur. In some methods of use, the surgeon can correct for changes inorientation by aligning the incidence of light from the opticalcomponent 174, 194 with the marking on the femur. In some methods ofuse, the surgeon manually realigns the femur to take another measurementof the point. In some methods of use, the method can require obtaining asingle point on the femur. The single point can be a mark. The singlepoint can be a tracker 784 or other fixture such as a screw or pin. Thesingle point can be an anatomical landmark. The single point can be aburr or divot in the femur. The point can be registered by the probe 778intra-operatively each time the leg length and/or joint offset is to bemeasured.

Before navigation systems, such as system 700, surgeons did not takemeasurements intra-operatively. Rather, surgeons typically looked at thecup placement during a procedure and determined whether current cupplacement looked like previous cup placements. The surgeon wouldvisually confirm cup placements during surgery and past experience inviewing post-operative images. The surgeon would determine if thecurrent cup placement was likely to correlate to the correct abductionand anteversion angles post-operatively. The surgeon would look at thecup placement and determine that the placement looks like 40 degrees×15degrees based on their experience looking at post-operative images. Thesurgeon's confidence in the procedure would be based on theircorrelation of cup placement and post-operative images.

For the system 700, the user is provided with an output that assists auser to navigate to proper cup placement. The output can be abductionand anteversion angles displayed on the surgical orientation device 172.The user can navigate to the desired abduction and anteversion angles bymoving components of the system 700, such as the impactor 300A or anyimpactor with the universal impactor adapter 350, 352. When the userplaces the cup at the desired abduction and anteversion angles, the userwants to see the same or similar angle on post-operative images. Theuser's confidence in the navigation of the system 700 increases if theabduction and anteversion angles produced by the system 700 match thepost-operative images. The vertical plane, determined from gravity asdescribed herein, can match the plane used in post-operative images. Insome embodiments, the vertical plane may be similar to the referenceplane of imaging techniques. In some methods of use, with some patients,the vertical plane provides abduction and anteversion angles thatclosely match post-operative images.

In some methods of use, as described herein, the method can include oneor more of the following steps. The method can include recording theposition of a probe 787 as the probe touches the point after replacingthe hip joint. The method can include comparing the position of a probeas the probe touches the point to the position recorded before replacingthe hip joint. In some embodiments, the surgical orientation device 172compares two or more measurements of the point. In some embodiments, thesurgical orientation device 172 compares measurements of the pointbefore and after the cup is replaced. In some embodiments, the surgicalorientation device 172 can provide a visual output of the change in leglength. In some embodiments, the surgical orientation device 172 canprovide a visual output of the change in joint offset. In someembodiments, the surgical orientation device 172 can provide a visualoutput of the direction of change of leg length (e.g., longer orshorter). In some embodiments, the surgical orientation device 172 canprovide a visual output of the direction of change of joint offset(e.g., lateral).

In some methods of use, as described herein, the method can include oneor more of the following steps. The method can include confirming theleg length after replacing the hip joint. The method can includeconfirming joint offset after replacing the hip joint. When measuringchanges in leg length and/or lateral joint offset, the apparent changesare sensitive to changes in the orientation of the femur relative to thepelvis. In some methods, the changes are particularly sensitive to theabduction angle. The changes are moderately sensitive to the rotationabout the mechanical axis of the femur. The optical component 174, 194can be used to verify the orientation of the femur relative to thepelvis before and after replacing the hip joint. In some methods,confirming the leg length and/or joint offset can include obtaining asingle point of the femur. The method of use can include the step ofmanually realigning the femur about the center of rotation (COR) of thehip

In some methods of use, as described herein, the method can include oneor more of the following steps. The method can include projecting lightafter replacing the hip joint. The method can include comparing theposition of the light before and after replacing the hip joint. Themethod can include comparing the incidence of light after replacing thehip joint with the one or more marks made before replacing the hipjoint. The method can include the comparing the incidence of light afterreplacing the hip joint with the two or more marks made before replacingthe hip joint. The method can include comparing the incidence of lightafter replacing the hip joint with a line made before replacing the hipjoint.

In some methods of use, as described herein, the method can include oneor more of the following steps. The method can include confirming theposition of the leg relative to the pelvis after replacing the hipjoint. The method can include confirming the position of the femurrelative to the pelvis after replacing the hip joint. The opticalcomponent 174, 194 can be useful to measure the orientation of the legrelative to pelvis during preoperative baseline and postoperatively. Thesurgeon can correct for changes in orientation by repositioning the legbased on the incidence of light. These marks can guide the surgeon inreplicating the orientation of the leg relative to the pelvis each timea leg length measurement or joint offset measurement is needed. Theoptical component 174, 194 can be used in conjunction with the posteriorapproach described herein.

In some embodiments, the surgeon can verify the home position aftermeasuring leg length and/or joint offset. The second assembly 706 can becoupled to the first assembly 704. The first assembly 704 can be coupledto the fixation base 702. In some techniques, the distal end 780 of theprobe 778 can be engaged with a point on the fixation base 702, such asthe divot 730. The user can enter an input to record the home position.In some methods of use, the home position remains fixed relative to thepelvis throughout the procedure. In some embodiments, the surgicalorientation device 172 can indicate a change in the home point. Thenumber displayed may not be zero due to mechanical play and noise of theorientation sensing device 204. In some methods of use, if displayednumber is greater than 3 mm, then the surgeon can verify all referencesensor attachments and jig connections are correct and secure beforerepeating. In some methods of use, if displayed number is greater than 3mm, then surgeon can repeat registration of the point or alignment ofthe femur. In some methods of use, repeating registrations will resultin a loss of all previous registrations. In some methods of use, thesurgeon determines whether the fixation base 702 has moved. In somemethods of use, the surgeon can end the procedure. In some methods ofuse, ending the procedure can result in loss of previous registrations.In some methods of use, ending the procedure can result in informationbeing stored. In some methods of use, the leg length is stored. In somemethods of use, the joint offset is stored. In some methods of use, thetarget angles are stored. In some methods of use, the fixation base 702and the fixation pins 710, 712 are removed prior to closure. In someembodiments, the surgical orientation device 172 is discarded. In someembodiments, the orientation sensing device 204 is reusable. In someembodiments, the optical component 174, 194 is reusable.

The table plane can be an improvement over a landmark-based referenceplanes for some patients. In some embodiments, the landmark-basedreference planes may differ from the vertical reference plane calculatedherein due to patient specific factors. For instance, pelvic tilt mayorient the landmark-based reference planes at an angle from the verticalreference plane. For instance, the patient's high body mass index mayimpact the ability to contact anatomical landmarks. For instance, theanatomical features of the reference points may not be visible and/orpalpable while the patient is in the lateral decubitus position of theposterior approach. For instance, the ipsilateral ASIS, thecontralateral ASIS, and/or the pubic symphysis may not be visible and/orpalpable. The patient specific factors can results in differencesbetween navigated cup angles from the landmark-based reference planesand angles measured post-operatively. In some methods of use, with somepatients, the landmark-based reference planes may not provide abductionand anteversion angles that match post-operative images.

Systems and methods described herein can improve prosthetic hip jointplacement using navigation. These hip procedures generally guide aprosthetic hip to an orientation within the acetabulum that minimizesthe chance of dislocation due to impingement of the femoral neck on thecup or on bones around the acetabulum or other reasons related tosuboptimal orientation of the prosthetic. Various techniques leveragepopulation averages of proper placement while others are amenable topatient specific refinements.

C. Navigation Using One or More Reference Planes with Anterior Approach

1. Methods for Anterior Approach

FIGS. 1-5C illustrate a hip navigation system 600 adapted to navigate ahip joint procedure from an anterior approach. FIGS. 7-10D illustratehip navigation system 700 adapted to navigate a hip joint procedure froman anterior approach. While the method is described with respect tosystem 600, any systems described herein or in the followingpublications can be utilized: U.S. Pat. Pub. No. 2016/0242934, filedMar. 10, 2015; U.S. Pat. Pub. No. 2014/0052149 filed Mar. 13, 2013; U.S.Pat. Pub. No. 2010/0137871 filed Sep. 10, 2009, all of which areincorporated by reference in their entirety. Anterior approach to hipreplacement advantageously can be less invasive than posterior approach.In particular, the anterior approach can enable smaller incisions, lesssoft tissue dissection, and shorten recovery time for patients.

In some embodiments, the navigation system 600 is configured to locate arelevant anatomical feature to aid in proper placement of a prosthetichip joint. In some methods, pre-operative imaging techniques are used.In some methods of use, the surgeon can use a standing or supineanteroposterior (AP) pelvic x-ray. FIG. 21 shows standing AP radiographtaken with patient standing with feet in neutral rotation and shoulderwidth apart in stance. The x-ray tube-to-film distance should be 120 cm,with the crosshairs centered on the midpoint between the superior borderof the pubic symphysis and a line drawn connecting the anterior superioriliac spines (ASIS). The coccyx should be centered in line with thepubic symphysis, and the iliac wings, obturator foramina andradiographic teardrops should be symmetrical in appearance. Forappropriate pelvic inclination or abduction, a 1-3 cm gap should be seenbetween the tip of the coccyx and the superior border of the pubicsymphysis. This positioning can be important for measuring the patientspecific Rim Teardrop (RT) angle.

To obtain the patient specific Rim Teardrop (RT) angle from the APpelvic x-ray the surgeon can complete one or more of the followingsteps. The surgeon can draw a line on the x-ray connecting the bottom ofthe teardrops. The surgeon can draw a line from the most lateral pointon the rim of the acetabulum (R) on the operative side through thebottom of the teardrop (T) to the horizontal inter-teardrop line. Ifosteophytes are present on the rim (R), the surgeon can draw a linethrough the most lateral osteophyte. The surgeon can measure the anglebetween the inter-teardrop line and the RT line just drawn. This patientspecific RT abduction angle can be an input for the system 600, 600A.

FIG. 22 shows the patient positioning for the anterior hip approach. Inthe anterior hip approach, the patient should be placed in the supineposition. When positioning the patient prior to surgery, the surgeonshould take care to align the spine and femur of a patient in ahorizontal plane parallel to the long edge of the operating table. Thesurgeon can verify that patient is positioned in an appropriateposition, e.g., in a supine position.

FIG. 23 shows the system 600 adapted to navigate a hip joint procedurewith reference to anatomical landmarks from an anterior approach. Thesystem 600 can include the orientation sensing device 204, not shown inFIG. 23. The system 600 can be adapted for either a posterior approachor an anterior approach. In the anterior approach, the patient is in thesupine position.

The surgical orientation device 172 and the orientation sensing device204 can be turned on before the procedure begins. If the system can beused in a knee or hip procedure, one method can involve a surgeonselecting a module corresponding to the hip. If the system can be usedin a posterior or anterior approach, one method can involve a surgeonselecting a module corresponding to the anterior approach. The surgicalorientation device 172 can include a display screen. The surgicalorientation device 172 can include a user interface, such as buttonswhich can be depressed by the user. The display screen can confirm thecommunication between the surgical orientation device 172 and theorientation sensing device 204.

The system 600 can be partially assembled for calibration as shown inFIG. 12A. In some embodiments, the first assembly 604 can be assembled.The pelvic bracket 638 can be coupled to the extension 644, if separatecomponents. The surgical orientation device 172 can be coupled to themount 646. In some techniques, the extension 670 can be coupled to thesecond coupler 648. The orientation sensing device 204 can be coupled tothe mount 672. The surgical orientation device 172 and the orientationsensing device 204 form a general V-shaped configuration, similar to theorientation shown in FIG. 12A. The orientation sensing device 204 can befixed in position relative to the surgical orientation device 172.

The surgical orientation device 172 and the orientation sensing device204 can be calibrated. The surgical orientation device 172 can be restedon a level horizontal surface with the display horizontal (facing up).The surgeon can hold the assemblies 604, 606 steady until the surgicalorientation device 172 indicates completion. The orientation sensingdevice 204 can be rested on a level horizontal surface with the displayvertical (facing user). The surgeon can hold the assemblies 604, 606steady until the surgical orientation device 172 indicates completion.The surgical orientation device 172 can be rested on a level horizontalsurface with the display pointed sideways (left side). The surgeon canhold the assemblies 604, 606 steady until the surgical orientationdevice 172 indicates completion. The surgical orientation device 172 canbe rested on a level horizontal surface with the display horizontal(facing up) again. The surgeon can hold the assemblies 604, 606 steadyuntil the surgical orientation device 172 indicates completion. Otherorientations of the surgical orientation device 172 and the orientationsensing device 204 are contemplated for calibration.

The user can remove the required instruments and prepare the instrumentsfor use. FIG. 18A illustrates an impactor 300A. As described herein, theimpactor 300A can include the fourth coupler 342 to couple the impactor300A to the orientation sensing device 204. In some methods, anyimpactor can be used with the systems and methods described herein. Theuniversal impactor adapter 350, 352 can provide the fourth coupler 342to couple the impactor to the orientation sensing device 204. In somemethods of use, the orientation sensing device 204 can be coupled to theimpactor 300A. In some methods of use, the orientation sensing device204 can be coupled to any impactor via the universal impactor adapter350, 352. The orientation sensing device 204 can determine cup anglesrelative to a reference plane as the impactor is moved. As describedherein, the impactor 300A can include a shell 312A. The movement of theshell 312A is cushioned by a plurality of spring members 340, 344 whichare configured to absorb at least some of the shock of the impact on theimpactor 300A. The shell 312A can include a fourth coupler 342. Thispermits the orientation sensing device 204 to couple to the shell 312A.The impactor 300A can be configured to be modified to suit any of aplurality of hip prostheses. For example, a plurality of tip components348 can be provided in a kit where each tip component is attachable toand detachable from a distal end of the shaft of the impactor 300A. Theacetabular shell can be threaded onto a tip component 348. The user canselect the appropriate shell adapter for the desired impactor.

As described herein, any impactor can be utilized. The surgeon canutilize the universal impactor adapter 350, 352. The universal impactoradapter 350, 352 can include a fourth coupler 342. This permits theorientation sensing device 204 to couple to the impactor. The universalimpactor adapter 350, 352 can form any rigid connection to the impactor.While magnets and clamps are described herein, any mechanical connectionbetween the universal impactor adapter 350, 352 and the impactor iscontemplated. The impactor can suit any of a plurality of hipprostheses. For example, a plurality of tip components 348 can beprovided in a kit where each tip component is attachable to anddetachable from a distal end of the shaft of the impactor. The impactorcan suit a particular hip prosthesis. The tip of the impactor can bedesigned to interface with a single acetabular shell. The acetabularshell can be threaded onto the impactor. The universal impactor adapter350, 352 can allow any impactor to be used with the orientation sensingdevice 204 as described herein.

The user can interact with the surgical orientation device 172. If thesystem can be used in either hip procedure, one method can involve asurgeon selecting a module corresponding to the right hip or the lefthip. In some methods of use, the user can input a target cup abductionangle. This is the radiographic abduction angle defined as the coronalplane projection of the angle between the acetabular axis and thelongitudinal axis of the body. Abduction and adduction are also used todescribe movement of the limb within the coronal plane. In some methodsof use, the user can input a target cup anteversion angle. This is theRadiographic Anteversion angle defined as the angle between theacetabular axis and the coronal plane.

The probe 678 can be calibrated. The extension 670 can be decoupled fromthe second coupler 648. The second assembly 606 can be assembled asshown in FIG. 12B. The first assembly 604 can be coupled to the secondassembly 606 as shown in FIG. 12B. In some methods of use, the system600 can include a calibration fixture 690. The first assembly 604 andthe second assembly 606 can be mounted to the calibration fixture 690.The calibration fixture can include a plurality of points for the probe678 to contact.

The probe 678 can contact a center hole at the base of the calibrationfixture 690 to calibrate a center point. The user can depress a buttonwhen the probe 678 is placed. The probe 678 can contact a left hole atthe base of the calibration fixture 690 to calibrate a left point. Theuser can depress a button when the probe 678 is placed. The probe 678can contact a right hole at the base of the calibration fixture 690 tocalibrate a right point. The user can depress a button when the probe678 is placed. The calibration fixture 690 can be utilized prior to theprocedure. The calibration fixture 690 can be located away from thepatient, for instance on a back table. Other calibration fixtures andjigs are contemplated.

The system 600 can be attached to the pelvis as shown in FIG. 23. Theuser can position the system 600 such that the system 600 has solid andstable mount for attachment of the instrumentation to the pelvis. Insome methods of use, all measurements and references are based off theinitial registration process and any movement of the first assembly 604after will result in error in the resulting readouts of cup position. Insome methods, the fixation pins 610, 612 are placed in the ipsilateraliliac crest in a parallel fashion. The fixation pins 610, 612 are placedin a similar fashion to placement of pins for pelvic external fixation.The fixation pins 610, 612 enter the iliac wing at its most superiorsurface and travel between the tables of the inner and outer bone of theiliac wing.

In order to prevent obstruction of subsequent femoral exposure andbroaching with the anterior approach, in some methods of use, the mostanterior fixation pin should be placed 2-4 cm posterior to the ASIS. Itis also helpful to evaluate the patients pre-operative x-rays to assessthe relative angle that will allow for passage of the fixation pins 610,612 within the bone. The most optimal position for the fixation pins610, 612 is to enter at approximately a 45 degree angle from theanterior pelvic plane to allow the pins to enter into the thickersupra-acetabular bone along the anterior column. In some methods of use,fixation pins 610, 612 that are passed at an angle greater than 45degrees are at risk for exiting the cortical bone where the ilium thinsmore posteriorly.

The fixation pins 610, 612 are designed with a pointed tip to allow forsecure placement while starting through the thicker outer cortical bone.This decreases risk of pin slippage and aberrant placement. It is alsoimportant for the user feel for any significant resistance when passingthe fixation pins 610, 612 to an appropriate depth to avoid perforatingthe cortical bone. If there is concern about pin location, the user mayaim more to the outer iliac wall. In some methods of use, the fixationpins 610, 612 can be stabilized if they are placed at least half theirlength into the bone. This will provide a stable construct with themount. The fixation base 602 has been designed to allow for parallelplacement with the anterior pelvic plane if the pins are placed at 45degrees.

The fixation pins 610, 612 can be inserted into the bone. In sometechniques, one or more of the fixation pins 610, 612 are positioned asdescribed herein. In some techniques, one or more of the fixation pins610, 612 are positioned on the iliac crest. In some techniques, one thefixation pins 610, 612 is positioned on the iliac crest 2-4 cm posteriorto ASIS. In some techniques, the other fixation pins 610, 612 ispositioned 2 cm posterior to the first fixation pin. The fixation base602 can be slid over the fixation pins 610, 612 to the level of theskin. The fixation devices 624 of the fixation base 602 can be tightenedto secure the fixation base 602 to the fixation pins 610, 612. In somemethods of use, the fixation base 602 must be attached prior todislocating the hip.

The system 600 can be assembled as shown in FIG. 1. The orientationsensing device 204 can be coupled to the probe 678. In some embodiments,the orientation sensing device 204 and/or the probe 678 include indiciasuch as arrows to facilitate alignment. The first assembly 604 can besecured to the fixation base 602 with the surgical orientation device172 attached. The first assembly 604 can be secured by pushing on thelock lever 640, as described herein. The second assembly 606 can besecured to the fixation base 602 with the orientation sensing device 204attached. In some embodiments, the second assembly 606 and/or thefixation base 602 include indicia such as arrows to facilitatealignment.

The surgical orientation device 172 can be aligned with the sagittalplane. The system 600 can be placed such that the probe 678 can reachall required landmarks defining the Anterior Pelvic Plane. The fixationbase 602 can be adjusted. In some methods of use, the fixation base 602can be slid along the fixation pins 610, 612. In some methods of use,angle or tilt of the fixation base 602 can be adjusted. Afteradjustment, the screws on the fixation base 602 can be tightened tosecure the fixation base 602 to the fixation pins 610, 612 for theremainder of the procedure.

The surgeon can register a parked configuration or home position. Insome techniques, the distal end 680 of the probe 678 can be engaged witha point on the fixation base 602, such as the divot 630. The probe 678can be vertical in the home position. The orientation sensing device 204can be vertical in the home position. The distal end of the probe 678can be curved or bent to facilitate locating anatomical landmarks orpoints.

When registering points, the user can hold the probe 678 close to thedistal end 680 to maximize accuracy of the measurement of the point.When interacting with the surgical orientation device 172, the user cansupport the back of the surgical orientation device 172 to avoid flexingthe fixation pins 610, 612 and/or the fixation base 602. The user canregister a point by pressing a button of the surgical orientation device172. If the registration is not accepted, the user can keep the probe678 stationary and press the button again.

The surgeon can position the distal end 680 of the probe 678 at variousanatomical landmarks or points. FIG. 24 illustrates the anatomy of thehip. As illustrated by FIG. 24, two landmarks are circled. The landmarksinclude the two anterior superior iliac spines (ASIS) which are bonyprojections of the iliac bone. The anterior superior iliac spines can bevisualized and/or palpitated by the user during surgery. The anteriorsuperior iliac spine is the anterior extremity of the iliac crest of thepelvis. The inter-ASIS line extends between these landmarks. Theinter-ASIS line extends between the ipsilateral ASIS and thecontralateral ASIS. In other methods of use, other landmarks are used.Other landmarks that could be used include locations on the ilium,ischium, pubis, anterior insertion point of trans-acetabular ligament tothe ischium, mid-point of the inferior aspect of the acetabular notch,the anterior superior iliac spine, anterior inferior iliac spine,convergence of the acetabulum and anterior inferior iliac spine, as wellas the other landmarks known in the art.

The system 600 has one or more processors that receive(s) data anddetermines the relative position and/or orientation of these anatomicallandmarks when the probe 678 contacts the anatomical landmark. The datacan be generated by inertial sensors, as discussed elsewhere herein, orother types of sensors of the system 600. Preferably the sensors aresmall enough to be mounted on or in handheld housings or embedded in theinstruments, such as the surgical orientation device 172 and theorientation sensing device 204. The system 600 preferably also has amemory device to at least temporarily store the position of thesepoints. The system 600 preferably also has the ability to at leasttemporarily store the relevant position and/or orientation data when theprobe 678 contacts the anatomic landmarks. In some methods of use, thesystem 600 records the position and/or orientation of the probe 678 whenthe probe 678 contacts each anatomic landmark or point. In some methodsof use, the system 600 stores the recorded position and/or orientationof the probe 678 during the length of the procedure. In some methods ofuse, the system 600 stores the recorded position and/or orientation ofthe probe 678 until the system is powered off.

FIGS. 25A-25D illustrate method steps to calculate the Anterior PelvicPlane. The Anterior Pelvic Plane can be defined as a plane created bythe two anterior superior iliac spines (ASIS) and the anterior surfaceof the pubic symphysis. Three points provide adequate information tocalculate a plane. The system 600 can generate the Anterior Pelvic Planeby registering Point 1, Point 2, and Point 3. These anatomical featuresare visible and/or palpable while the patient is in a supine position.In some methods, the probe 678 registers the Anterior Pelvic Plane withdirect contact of anatomical landmarks when the patient is in the supineposition. The system 600 is then able to provide the user navigationdata of the orientation of a hip instrument (e.g., the impactor 300A orany impactor with universal impactor adapter 350, 352) with respect tothe Anterior Pelvic Plane. In some embodiments, the system 600 is ableto provide the user navigation data in real-time. In the anteriorapproach, the patient is positioned on his/her back and the AnteriorPelvic Plane is oriented substantially horizontally, e.g., substantiallyparallel to the plane of the table on which the patient is positioned.

FIG. 25A illustrates the approximate location of three points of theAnterior Pelvic Plane. The surgeon can register Point 1, Point 2, andPoint 3. The illustrated embodiment shows Point 1 on the left hip, Point2 on the right hip, and Point 3 on the right hip. Other configurationsare contemplated. For some procedures on a patient's left hip, Point 1is on the left hip and Point 2 is on the right hip. For some procedureon a patient's right hip, Point 1 is on the right hip and Point 2 is onthe left hip. Other methods are contemplated. In some methods, Point 1is the ipsilateral ASIS. In some methods, the distal end 680 of theprobe 678 is placed at the ipsilateral ASIS landmark. The probe 678 canbe immobilized and the position and/or orientation of the orientationsensing device 204 can be recorded by the surgical orientation device172. The surgeon can enter an input to register Point 1 (e.g., depress abutton on the surgical orientation device 172). Other ways of enteringan input include interacting with a touchscreen, using a verbal command,touching an icon, holding the probe 678 steady for a period of time,and/or reaching the end of a countdown clock, etc. The surgicalorientation device 172 can indicate that Point 1 was recorded.Additionally, the distance that the probe 678 is extended, as capturedby the camera 184, to contact the ipsilateral ASIS can be recorded bythe orientation device 172. The process to record the ipsilateral ASIScan be repeated for one or more additional points.

In some methods, Point 2 is the contralateral ASIS. In some methods, thedistal end 680 of the probe 678 is placed at the contralateral ASISlandmark. The probe 678 can be immobilized and the position and/ororientation of the orientation sensing device 204 can be recorded by thesurgical orientation device 172. The surgeon can enter an input toregister Point 2 (e.g., depress a button on the surgical orientationdevice 172). The surgical orientation device 172 can indicate that Point2 was recorded. Additionally, the distance that the probe 678 isextended, as captured by the camera 184, to contact the contralateralASIS can be recorded by the orientation device 172. The process torecord the contralateral ASIS can be repeated for one or more additionalpoints.

In some methods, Point 3 is the anterior surface of the pubic symphysis.In some methods, the distal end 680 of the probe 678 is placed at thepubis landmark. In some methods, either pubic tubercle may be used asPoint 3. In some embodiments, the contralateral pubic tubercle is usedas Point 3. The probe 678 can be immobilized and the position and/ororientation of the orientation sensing device 204 can be recorded by thesurgical orientation device 172. The surgeon can enter an input toregister Point 3 (e.g., depress a button on the surgical orientationdevice 172). The surgical orientation device 172 can indicate that Point3 was recorded. Additionally, the distance that the probe 678 isextended, as captured by the camera 184, to contact the pubic symphysiscan be recorded by the orientation device 172. The process to record thepubic symphysis can be repeated for one or more additional points.

The distance related to the extension of the probe 678 can be used inconjunction with the positional and/or orientation data from theorientation sensing device 204. In some methods, the orientation sensingdevice 204 converts the image of the camera 184 into an extensionmeasurement of the probe 678. In some embodiments, the surgicalorientation device 172 converts the image of the camera 184 into anextension measurement of the probe 678. When registering the anatomicalpoints, the camera 184 captures an image of the marking 682. The camera184 can read the marking 682 to provide accurate determination of thetranslational position of the probe 678 relative to the dock 662. Thecamera 184 can be directly above the marking 682. In some methods, thecamera 184 can read a binary code of the marking 682.

The surgical orientation device 172 can use the length measurement fromthe camera 184 and the data from the orientation sensing device 204 todetermine the location of the distal end 680 of the probe 678. In someembodiments, the surgeon will enter an input (e.g., depress a button) tocollect data from the orientation sensing device 204. In some methods,the surgeon will enter an input (e.g., depress a button) to collect datafrom the camera 184. In some embodiments, the surgeon will enter aninput (e.g., depress a button) to collect data from the orientationsensing device 204 and the camera 184 simultaneously. In some methods,the orientation sensing device 204 and/or the camera 184 will only senddata if the orientation sensing device 204 is stable or non-moving.

Once the foregoing points of the pelvis have been navigated and the datarecorded into the surgical orientation device 172, the Anterior PelvicPlane can be calculated from data indicating the navigated points. Thesystem 600 can calculate the Anterior Pelvic Plane from the three pointsrecorded by the system 600. The three points are shown in FIG. 12A. FIG.25B illustrates the inter-ASIS line. The inter-ASIS line connects Point1 and Point 2. The inter-ASIS line provides a straight line between theipsilateral ASIS and the contralateral ASIS. FIG. 25C illustrates thegeneral horizontal direction of the Anterior Pelvic Plane. The AnteriorPelvic Plane can be considered a horizontal plane that pivots about theinter-ASIS axis depending on the location of Point 3. FIG. 25Dillustrates the Anterior Pelvic Plane (APP) which is determined by Point3. The Anterior Pelvic Plane includes the ipsilateral ASIS, thecontralateral ASIS, and the anterior surface of the pubic symphysis.

As described herein, the system 600 can determine a reference plane. Theplane can be uniquely determined by any of the following: threenon-collinear points, a line and non-collinear point, two distinct butintersecting lines, or two parallel lines. In some methods of use, theAnterior Pelvic Plane is calculated based on three non-collinear points.In some methods of use, the Anterior Pelvic Plane is calculated based onipsilateral ASIS, contralateral ASIS, and the anterior surface of thepubic symphysis. In some methods of use, the orientation of the AnteriorPelvic Plane can be a baseline for placement of the cup portion of a hipprosthesis. The surgical orientation device 172 can display informationwith respect to the Anterior Pelvic Plane. In some methods of use, theabduction and anteversion angles in cup placement in total hiparthroplasty can be with respect to the Anterior Pelvic Plane. TheAnterior Pelvic Plane is cited in literature as a valid anatomical planeto guide cup placement. In some embodiments, the Anterior Pelvic Planeis determined by the surgical orientation device 172 and/or theorientation sensing device 204. In some embodiments, a reference frameis established by the Anterior Pelvic Plane. The Anterior Pelvic Planereference frame is a three dimensional reference frame. The AnteriorPelvic Plane reference frame is a reference frame that contains theAnterior Pelvic Plane. In some embodiments, the surgical orientationdevice 172 and/or the orientation sensing device 204 can provideorientation and/or position data related to the Anterior Pelvic Planereference frame. In some embodiments, the surgical orientation device172 can display orientation and/or position data relative to theAnterior Pelvic Plane reference frame.

FIGS. 26A-26D illustrate method steps to calculate a table plane. Anymethod to establish the table plane described herein or incorporated byreference can be utilized. The table plane can be a horizontal orgenerally horizontal plane. In some techniques, the operating table ishorizontal and the table plane approximates the plane of the table. Insome techniques, the table plane can be oriented relative to othersurface in the operating room. In some techniques, the floor ishorizontal and the table plane approximates the plane of the floor. Insome techniques, the wall is vertical and the table plane approximatelya plane perpendicular to the wall. In some techniques, the ceiling ishorizontal and the table plane approximates the ceiling. Other surfacesmay be use to approximate a horizontal plane. The table registrationestimates the coronal plane or frontal plane. The coronal plane is aplane that divides the body in anterior and posterior sections. Thecoronal plane is a horizontal reference plane when the patient is in thesupine position of the anterior approach. The orientation sensing device204 can register the operating table or perform table registration forthe anterior approach. The top surface of the operating table upon whichthe patient is positioned is positioned horizontally. The patient can bepositioned so that the coronal plane of the pelvis is level, e.g.,parallel to the table and/or also horizontal. The user can visuallyverify the coronal plane is level or can use devices to position thepatient's body to align the coronal plane with the plane of the topsurface of the table. In some embodiment, a reference plane based on theplane of the top surface of the table can be input into the system 600.

The table plane provides clinical value. In some techniques, the tableplane can provide a secondary reference plane to the Anterior PelvicPlane. In some embodiments, the table plane is determined completelyindependently of any anatomical landmarks. The table plane provides acheck against gross errors from the anatomical registrations. The tableplane provides a reference plane that is unaffected by pelvic tilt. Thetable plane provides a reference plane that is unaffected by errors inregistration due to soft tissue. The table plane appears in largeconsole navigation. The table plane is calculated based on properlyaligning the probe 678. In some methods of use, the alignment of theprobe 678 can be done entirely by eye. The table plane provides ahorizontal plane which may be useful for comparing the navigated cupangles to pre-operative and/or post-operative images. The pre-operativeand/or post-operative images, such as x-rays, are captured within ahorizontal reference plane. The table plane may provide a horizontalreference plane that approximates the horizontal reference plane ofimaging techniques.

During table registration, the probe 678 is coupled with the orientationsensing device 204. In some methods of use, the probe 678 and theorientation sensing device 204 are constrained. As one example, theprobe 678 can be coupled with other components of the first assembly 604and/or the second assembly 606. In some methods of use, the system 600is assembled, such that the first assembly 604 and the second assembly606 are coupled to the patient via the fixation pins 610, 612. There maybe mechanical constraints imposed by the pivot configuration of thesystem 600.

FIG. 26A illustrates the position of the probe 678 during tableregistration. The probe 678 is rotated and/or pivoted by the mount 658such that the probe 678 points in a direction that is parallel to thepatient's sagittal plane. The probe 678 can be extended toward thepatient's foot. The probe 678 can be aligned with the long axis of thebody. The probe 678 can be held substantially parallel to the plane ofthe table. Referring back to FIG. 22, the side view of the patientillustrates one line which is parallel to the table. During tableregistration, the probe 678 can be parallel to the table as viewed fromthe side. In some embodiments, the user can align the probe 678 with thehorizontal. The user can visually inspect the probe 678 from one or morelocations. For instance, the user can inspect the probe 678 from a topview and a side view. In some embodiments, the user can align the probe678 with the sagittal plane. The probe 678 can be parallel with thesagittal plane or a para-sagittal plane. The sagittal plane divides thebody into right and left parts.

FIG. 26B illustrates the table plane (TP) in a method of use. The probe678 can be immobilized and the position and/or orientation of theorientation sensing device 204 can be recorded by the surgicalorientation device 172. The user can enter an input to register thetable (e.g., depress a button on the surgical orientation device 172).The user can interact with a user interface on the surgical orientationdevice 172 to signal to the surgical orientation device 172 to capturethe position and/or orientation of the orientation sensing device 204.The surgical orientation device 172 can indicate that the table planewas recorded.

In some embodiments, information from one or more inertial sensors isused during table registration. As described herein, the orientationsensing device 204 and the surgical orientation device 172 can includeone or more inertial sensors. In some embodiments, the position and/orthe orientation of one or more inertial sensors can provide data relatedto the table plane. The one or more inertial sensors can detect gravityand provide a vector for the down direction. The table plane isconsidered a horizontal plane. In some methods of use, the vector forthe down direction can be used by the system to verify that the tableplane is a horizontal plane. In some embodiments, only the direction ofthe projection of the probe 678 onto a horizontal plane is used. In someembodiments, the table plane is determined by the surgical orientationdevice 172. In some embodiments, a reference frame is established by thetable plane. The table reference frame is a three dimensional referenceframe. The table reference frame can be determined by the orientationsensing device 204 and the surgical orientation device 172. The tablereference frame can be determined in a different way for the anteriorand posterior approach. For instance, different sensors of theorientation sensing device 204 and the surgical orientation device 172can be utilized to determine the table reference frame for the anteriorand posterior approach.

The table plane provides an estimation of the orientation of the coronalplane. The table plane may be recorded and stored in the system 600. Thesystem 600 can calculate cup angles based on the table plane based onthe assumption that the pelvis of the patient is correctly positionedduring registration of the table plane. In some methods of use, theabduction and anteversion angles in cup placement in total hiparthroplasty can be with respect to the plane determined during tableregistration.

In some techniques, the table registration can be completed prior todislocating the hip. The torque applied during dislocation can movepelvis away from the correct initial alignment. In some techniques, thefixation base 602 cannot be adjusted by the user after tableregistration. For instance, the user cannot adjust the fixation base 602relative to the pins 610, 612. The fixation base 602 remains in positionfor the rest of the procedure. In some techniques, the pelvic bracket638 cannot be adjusted by the user after table registration. The pelvicbracket 638 remains in position for the rest of the procedure. In sometechniques, angle of the pelvic bracket 638 relative to the fixationbase 602 cannot be changed after table registration. In some techniques,the probe 678 cannot be replaced with a different probe after tableregistration. The same probe 678 is used for the remainder of theprocedure.

FIGS. 26C and 26D illustrate another outcome of table registration. Insome methods of use, the probe 678 can be oriented at in an infinitenumber of angles from horizontal during table registration. Forinstance, when viewed from the side similar to the view of FIG. 22, theprobe 678 may appear to be aligned with the coronal plane. However, thetop view, shown in FIG. 26C, shows that the probe is angled relative tothe sagittal plane. The user can introduce other errors based, in part,on the point of view of the user when probe 678 is positioned. FIG. 26Dshows the resulting table plane (TP). FIGS. 13B and 26D show twodifferent planes calculated during table registration. In both methodsof use, the probe 678 is positioned parallel to the operating table.However, the two planes are angled based on the positioning of the probe678. In some methods of use, there may be a potential for misalignmentdue to improper positioning of the probe 678.

FIGS. 27A-27D illustrate method steps to calculate an Adjusted Plane(ADJUSTED). FIG. 27A illustrates the inter-ASIS line. The inter-ASISline connects Point 1 and Point 2 discussed above in connection withFIG. 25A. The inter-ASIS line provides a straight line between theipsilateral ASIS and the contralateral ASIS. As described herein, Point1 and Point 2 can be recorded by the system 600. Point 1 and Point 2 canbe recorded as part of a method to calculate the Anterior Pelvic Plane.Point 1 and Point 2 can be recorded independently from a method tocalculate the Anterior Pelvic Plane. The Adjusted Plane can becalculated in addition or as an alternative to the Anterior PelvicPlane. In some methods, Point 1 and Point 2 are used to calculate theAnterior Pelvic Plane and the Adjusted Plane. The system 200 can storePoint 1 and Point 2 for the Anterior Pelvic Plane and the AdjustedPlane. In some methods, Point 1 and Point 2 are registered only once forthe Anterior Pelvic Plane and the Adjusted Plane.

The system 600 can generate the Adjusted Plane by registering Point 1and Point 2. These anatomical features are visible and/or palpable whilethe patient is in a supine position. The system 600 is then able toprovide the user navigation data of the orientation of a hip instrument(e.g., the impactor 300A or any impactor with the universal impactoradapter 350, 352) with respect to the Adjusted Plane. In some methods ofuse, the navigation data is provided in real-time. In the anteriorapproach, the patient is positioned on his/her back and the AdjustedPlane is oriented horizontally, e.g., parallel to the plane of the tableon which the patient is positioned.

FIG. 27A illustrates the approximate location of two points of theAdjusted Plane. The surgeon can register Point 1 and Point 2, asdescribed herein. In some methods, Point 1 is the ipsilateral ASIS. Insome methods, the distal end 680 of the probe 678 is positioned at theipsilateral ASIS landmark. While the probe 678 is contacting thelandmark, the position and/or orientation of the orientation sensingdevice 204 can be transmitted to the surgical orientation device 172.While the probe 678 is contacting the landmark, the distance that theprobe 678 is extended, as measured by the camera 184, can be transmittedto the surgical orientation device 172. The user can enter an input torecord Point 1 (e.g., depress a button on surgical orientation device172). The surgical orientation device 172 can provide an indication thatPoint 1 was recorded, such as a visual or audial cue.

In some methods, Point 2 is the contralateral ASIS. In some methods, thedistal end 680 of the probe 678 is placed at the contralateral ASISlandmark. In some methods, the distal end 680 of the probe 678 ispositioned at the contralateral ASIS landmark. While the probe 678 iscontacting the landmark, the position and/or orientation of theorientation sensing device 204 can be transmitted to the surgicalorientation device 172. While the probe 678 is contacting the landmark,the distance that the probe 678 is extended, as measured by the camera184, can be transmitted to the surgical orientation device 172. The usercan enter an input to record Point 2 (e.g., depress a button on surgicalorientation device 172). The surgical orientation device 172 can providean indication that Point 2 was recorded, such as a visual or audial cue.

The Adjusted Plane is found by a rotation of the Anterior Pelvic Planeabout the inter-ASIS line to be perpendicular to the force of gravity.The Adjusted Plane utilizes a measurement of gravity. As describedherein surgical orientation device 172 comprise one or more inertialsensors. As described herein orientation sensing device 204 comprise oneor more inertial sensors. In some embodiments, inertial data from one ormore inertial sensors is used to calculate the Adjusted Plane. In someembodiments, the position and/or the orientation data of one or moreinertial sensors is used to calculate the Adjusted Plane. The surgicalorientation device 172 and/or the orientation sensing device 204 cancomprise an accelerometer, which can provide a measurement of thedirection of gravity. In some embodiments, the surgical orientationdevice 172 and/or the orientation sensing device 204 includes a sensorto detect the direction of gravity. The surgical orientation device 172and/or the orientation sensing device 204 can be sensitive to thedirection of gravity. The one or more inertial sensors can provide avector aligned with vertical, e.g., for the down direction. In someembodiments, the surgical orientation device 172 and/or the orientationsensing device 204 includes a three axis accelerometer to detectorientation relative to or of gravity.

In some embodiments, the surgical orientation device 172 includes anaccelerometer. In some embodiments, the orientation sensing device 204includes an accelerometer. The accelerometer at rest can measure theacceleration due to Earth's gravity. The accelerometer can measure theacceleration from gravity straight downward or vertically. In someembodiments, the accelerometer can detect the magnitude and direction ofthe force of gravity. The accelerometer can produce a vertical vector.The accelerometer can produce a horizontal vector by transforming thevertical vector (e.g., by rotation of 90 degrees). The accelerometer canprovide orientation and/or position data such that the Adjusted Plane isperpendicular to the force of gravity.

The surgical orientation device 172 and/or the orientation sensingdevice 204 can provide a reference to gravitational zero. Gravitationalzero, as referred to herein, refers generally to an orientation in whichan axis of a sensor is perpendicular to the force of gravity, andthereby experiences no angular offset, for example tilt, pitch, roll, oryaw, relative to a gravitational force vector.

In some methods of use, the measurement of gravity can be taken at anypoint during the procedure. The measurement of gravity can be takenduring pre-operative calibration. The measurement of gravity can betaken during table registration. In some methods, the probe 678 isplaced horizontally. The placement of the probe 678 can provideverification that the gravitational measurement is free from grosserrors. FIG. 27B illustrates one position of the probe 678 to calculatethe direction of gravity when the probe 678 is generally horizontal. Theprobe 678 is rotated and/or pivoted by the mount 658 such that the probe678 points in a direction that is parallel to the patient's sagittalplane. The probe 678 can be extended toward the patient's foot. Theprobe 678 can be aligned with the long axis of the body. The probe 678can be held substantially parallel to the plane of the table. In someembodiments, the user can align the probe 678 with the horizontal. Theuser can visually inspect the probe 678 from one or more locations. Forinstance, the user can inspect the probe 678 from a top view and a sideview. In some embodiments, the user can align the probe 678 with thesagittal plane. The probe 678 can be parallel with the sagittal plane ora para-sagittal plane. The sagittal plane divides the body into rightand left parts. As described herein, the orientation sensing device 204can be positioned horizontally to measure gravity. As described herein,the probe 678 coupled to the orientation sensing device 204 can bepositioned horizontally or substantially horizontally to measuregravity.

The probe 678 can be held in position or immobilized. The positionand/or orientation of the orientation sensing device 204 can be recordedby the surgical orientation device 172. The user can enter an input whenthe probe 678 is positioned horizontally (e.g., depress a button on thesurgical orientation device 172). The user can interact with a userinterface on the surgical orientation device 172 to signal to thesurgical orientation device 172 to capture data of the orientationsensing device 204 when the probe 678 is positioned horizontally. Thesurgical orientation device 172 can indicate that data was recorded. TheAdjusted Plane can be calculated in addition or as an alternative to thetable plane. The system 200 can store gravitational zero forcalculations related to the Anterior Pelvic Plane. In some methods,gravitational zero is registered only once and utilized throughout theprocedure.

In some methods of use, the orientation sensing device 204 can bepositioned in other ways than horizontally to measure the direction ofgravity. In some methods of use, the orientation sensing device 204 canmeasure gravity when in the home position. In some methods of use, theorientation sensing device 204 can be positioned vertically orsubstantially vertically to measure gravity. In some methods of use, theorientation sensing device 204 can measure gravity when contacting apoint or anatomical landmark. In some methods of use, the orientationsensing device 204 can measure gravity when contacting Point 1. In somemethods of use, the orientation sensing device 204 can measure gravitywhen contacting Point 2. In some methods of use, the orientation sensingdevice 204 can measure gravity when contacting a point on the femur. Thepoint on the femur can be a mark, such as Fm described herein. The pointon the femur can be a structure. The point on the femur can be ananatomical landmark. In some methods of use, the orientation sensingdevice 204 can measure the force of gravity at any angular orientation.In some methods of use, the orientation sensing device 204 determine avertical vector of gravity when resting at any position.

In some embodiments, the surgical orientation device 172 measuresgravity. The surgical orientation device 172 can provide an indicationof the upward/downwards or vertical direction. The surgical orientationdevice 172 can produce a horizontal vector by transforming the verticalvector of gravity (e.g., by rotation of 90 degrees). In someembodiments, the surgical orientation device 172 remains stationary whenmeasuring gravity. In some embodiments, the surgical orientation device172 is coupled or affixed to the pelvis of the patient when measuringgravity. In some methods of use, the surgical orientation device 172 iscoupled to the patient via the fixation pins 610, 612 when measuringgravity. In some methods of use, the surgical orientation device 172 isconstrained when measuring gravity. As one example, the surgicalorientation device 172 can be coupled with other components of the firstassembly 604 and/or the second assembly 606. In some embodiments, theorientation sensing device 204 and the surgical orientation device 172both determine the direction of gravity. In some embodiments, inertialdata from two or more sensors are used to measure gravity.

FIG. 27C illustrates a horizontal direction of the Adjusted Plane. TheAdjusted Plane can be considered a horizontal plane that pivots aboutthe inter-ASIS line depending on the measurement of gravity. FIG. 27Dillustrates the Adjusted Plane. Once the foregoing points of the pelvishave been navigated and the data recorded into the surgical orientationdevice 172, the Adjusted Plane can be calculated from data indicatingthe navigated points and the gravity measurement. The Adjusted Planeincludes the ipsilateral ASIS and the contralateral ASIS. The AdjustedPlane includes the inter-ASIS line. The system 600 can combine thehorizontal vector with Point 1 and Point 2 to calculate the AdjustedPlane. In some embodiments, the Adjusted Plane can be considered ahorizontal plane determined by the direction of gravity. In someembodiments, the Adjusted Plane can be considered a horizontal planecontaining the inter-ASIS line.

As described herein, three anatomical landmarks are registered for theAnterior Pelvic Plane. The ipsilateral ASIS, the contralateral ASIS, andthe pubic symphysis, as registered by the probe 678, define the AnteriorPelvic Plane. As described herein, two anatomical landmarks areregistered for the Adjusted Plane. The two landmarks define theinter-ASIS line.

In some embodiments, the surgical orientation device 172 can provide acorrected reference frame by transforming, e.g., by rotating theAnterior Pelvic Plane about the inter-ASIS line based on the directionof gravity. In some embodiments, the surgical orientation device 172 canrotate the Anterior Pelvic Plane about the inter-ASIS line to provide acorrected reference frame that is aligned with horizontal. Themeasurement of gravity enables the surgical orientation device 172 torotate the Anterior Pelvic Plane. The measurement of gravity enables thesurgical orientation device 172 to establish the Adjusted Plane. Themeasurement of gravity enables the surgical orientation device 172 tocalculate the angle that the Anterior Pelvic Plane must rotate to bealigned with horizontal. In some embodiments, the orientation sensingdevice 204 can rotate the Anterior Pelvic Plane about the inter-ASISline based on the direction of gravity. The surgical orientation device172 and/or the orientation sensing device 204 can include hardware orsoftware to enable the transformation of, e.g., the rotation of, theAnterior Pelvic Plane based on the direction of gravity. The one or moreinertial sensors of the orientation sensing device 204 and/or thesurgical orientation device 172 can provide data to determine how totransform, e.g., to rotate, a plane containing the inter-ASIS axis to beperpendicular to the force of gravity. In some methods of use, thevector for the down direction can be used by the orientation sensingdevice 204 and/or the surgical orientation device 172 to determine ahorizontal plane containing the inter-ASIS axis. In some methods of use,inertial data related to gravity can be used by the system 600 todetermine the degree in which to rotate the Anterior Pelvic Plane aboutthe inter-ASIS axis to be horizontal.

The orientation of the Adjusted Plane can be a baseline for placement ofthe cup portion of a hip prosthesis. The surgical orientation device 172can display information with respect to the Adjusted Plane. In somemethods of use, the abduction and anteversion angles in cup placement intotal hip arthroplasty can be with respect to the Adjusted Plane. Insome embodiments, the Adjusted Plane is determined by the surgicalorientation device 172 and/or the orientation sensing device 204. Insome embodiments, a reference frame is established by the AdjustedPlane. The Adjusted Plane reference frame is a three dimensionalreference frame. The Adjusted Plane reference frame is a reference framethat contains the Adjusted Plane. In some embodiments, the surgicalorientation device 172 and/or the orientation sensing device 204 canprovide orientation and/or position data related to the Adjusted Planereference frame. In some embodiments, the surgical orientation device172 can display orientation and/or position data relative to theAdjusted Plane reference frame.

Once registration is complete, the user can proceed to proceed todislocate the hip, resect the femoral head, and prepare the acetabulum.The user can prepare the impactor and shell. The user can remove thesecond assembly 606 from the first assembly 604. The user can remove theorientation sensing device 204 from the probe 678. The user can dock theorientation sensing device 204 to the first assembly 604. The surgicalorientation device 172 and the orientation sensing device 204 form ageneral V-shaped configuration, similar to the orientation shown in FIG.12A.

The user can set the cup angle. The user can remove the orientationsensing device 204 from the first assembly 604. The orientation sensingdevice 204 and the surgical orientation device 172 can at this point beused to guide placement of the cup in the prescribed orientation. Thesurgeon can remove the extension 670 from the third coupler 668. Thesurgeon can couple the extension 670 to an impactor 300A, shown in FIG.18A. The surgeon can couple the extension 670 to any of the universalimpactor adapters 350, 352 described herein. The universal impactoradapter 350, 352 can be utilized to mount the fourth coupler 342 to anyimpactor. The fourth coupler 342 can allow the orientation sensingdevice 204 to couple to the impactor. The impactor can be configured tobe modified to suit any of a plurality of hip prostheses or the impactorcan be designed to suit a particular hip prosthesis.

The acetabular shell can be inserted into the acetabulum and positionedat the desired angle. The surgical orientation device 172 can guide thesurgeon in setting the appropriate cup angle. The surgical orientationdevice 172 can graphically display when the orientation sensing device204 is navigated to the desired abduction and anteversion angles. Thedesired abduction and anteversion angles can be pre-operative cup anglesentered by the surgeon during calibration. The surgical orientationdevice 172 can graphically display the abduction and anteversion anglesas the orientation sensing device 204 is moved. The user can alignimpactor at desired cup angle. Aligning a visual indicator of thesurgical orientation device 172 can guide the user to position theimpactor at the desired cup angles. The abduction and anteversion anglescan be displaced statically. The cup angles can be checked afterimpacting by repeating the proceeding steps.

The surgical orientation device can provide cup angles relative to anyreference plane, including those described herein. The Adjusted Planecan provide several advantages over the table registration. The AdjustedPlane can increase the accuracy of the table registration. For instance,the Adjusted Plane provides a verification of the horizontal directionof the probe 678 via a measurement of gravity. For instance, theAdjusted Plane improves placement of the horizontal plane by includinganatomical landmarks or points. For instance, the Adjusted Plane caninclude one or more anatomical locations. For instance, the AdjustedPlane can include an anatomical line. For instance, the Adjusted Planecan include the inter-ASIS line as described above. From a side view,the Adjusted Plane can look as though it is the same as the table plane.However, the Adjusted Plane includes the inter-ASIS line whereas thetable plane may not always include this line. The table registration mayintroduce some errors in orientating the horizontal plane. There may begreater accuracy in the Adjusted Plane since it orients the plane basedon anatomical landmarks and a measurement of gravity.

The surgical orientation device 172 can include indicia such as a targetor bullseye to indicate the pre-determined abduction and anteversionangles. The surgical orientation device 172 can include indicia such asa dot or cross-hair to indicate movement of the impactor. Aligning theindicia in the center of the target or bullseye can indicate that theimpactor is aligned with the predetermined cup angles. The indicia canmove in real-time. The surgical orientation device 172 can include areadout of the abduction and anteversion angles. The angles can becalculated in real-time. The angles can change as the impactor is moved.The user can have a set amount of time to align the impactor with thedesired cup angles. The user can enter an input once the desired cupangles are reached. In some methods, after the impactor is positionedrelative to the desired cup angles, the cup angles can be displayedstatically. The surgical orientation device 172 can provide informationregarding the pelvis or other information dynamically.

After positioning the cup, the user can attach the second system 606 tothe first system 604, similar to the configuration shown in FIG. 1. Theuser can verify the home position. In some techniques, a distal end ofthe probe 678 can be engaged with a point on the fixation base 602, suchas divot. The probe 678 can be vertical in the home position. Theorientation sensing device 204 can be vertical in the home position. Theuser can repeat registration if the home position has shifted. The usercan end the procedure. The user can remove the system 600 prior toclosure.

In some methods of use, the user can measure for leg length and jointoffset. At the surgeon's discretion the system 600 can be used tonavigate a condition, location and/or orientation of the femur prior tohip replacement. In some embodiments, a mark Fm as shown in FIG. 24 maybe made on the proximal femur. In some embodiments, a structure isattached to the femur, such as a pin. In some embodiments, a burr ordetent is made in the femur. Thereafter the orientation sensing device204 can be initialized or zeroed such as by placing it back in the homeposition. Thereafter, the distal end 680 of the probe 678 can be broughtinto contact with the femur mark Fm. The surgical orientation device 172can be signaled to record the orientation of the orientation sensingdevice 204. A distance from the point of attachment of the fixation pins610, 612 to the marked position on the femur can then be recorded in thesurgical orientation device 172. The position can be based on capturingthe markings 682 the probe 678 or probe inlay 676 by the camera 184, incombination with inertial data from the orientation sensing device 204.

If femoral landmark Fm is acquired in the procedure prior to separatingthe natural joint, the same landmark can be acquired after theprosthetic joint is placed to confirm that the replacement of the jointhas not changed either the length of the leg, the off-set of the legfrom the trunk of the patient or both. Thereafter, the distal end 680 ofthe probe 678 can be brought into contact with the same landmark (e.g.,Fm) acquired early in the procedure. The orientation of the orientationsensing device 204 and the extension of the probe 678 can be input intothe surgical orientation device 172. These data enable the surgicalorientation device 172 to output amounts of change in leg length and legoffset.

In some methods of use, the system 600 includes an optical component 174shown in FIG. 6A and/or the optical component 194 shown in FIGS. 6B-6C.In some embodiments, the optical component 174, 194 is a separatecomponent. In some embodiments, the optical component 174, 194 iscoupled to the first assembly 604. In some embodiments, the opticalcomponent 174 can be rotated relative to the first assembly 604, forinstance by a knob 176. The optical component 174, 194 can comprise oneor more lasers, which can be configured to project laser light. Theoptical component 174, 194 can provide a visual guide to replicate theoriginal position of the femur relative to the pelvis. The laser lightcan be used to project a point, a plane, and or a cross-hair onto atarget or targets, including but not limited to an anatomical feature orlandmark. The surgeon can mark one or more points along the line of theprojection of the optical component 174, 194. The surgeon can completeany steps described herein. The surgeon, thereafter, can verify the oneor more points are along the line of the projection of the opticalcomponent 174, 194. When measuring changes in leg length and lateraljoint offset, the apparent changes are sensitive to changes in theorientation of the femur relative to the pelvis. The user can repositionthe femur prior to measuring the change such that the orientation of thefemur relative to the pelvis is the same as that when the preoperativebaseline measurement was made.

Another method is to measure the orientation of the femur relative topelvis during preoperative baseline and postoperatively and then correctfor changes in orientation by doing a virtual rotation about thepostoperative center of rotation of the femur. The method may requireobtaining three points of the femur. The three points on the femur canbe marks or anatomical landmarks. The three points can be on a femurplate. The three points on the femur or femur plate may be registered bythe probe 678 to resolve for the femur orientation preoperatively andthen postoperatively each time the leg length is to be measured.

2. Adjusted Plane and Anterior Pelvic Plane Comparison

FIG. 28A illustrates a side view of the Anterior Pelvic Plane. TheAnterior Pelvic Plane includes the inter-ASIS line as described herein.FIG. 28B illustrates a comparison between the Anterior Pelvic Plane andthe Adjusted Plane. FIGS. 28A-1 and 28B-1 illustrate another side viewof the system where in the ASIS are aligned. FIG. 28B illustrates a sideview of the Anterior Pelvic Plane and the Adjusted Plane. FIG. 28Cillustrates a top view of the Anterior Pelvic Plane and the AdjustedPlane. As described herein, the Anterior Pelvic Plane and the AdjustedPlane both contain the inter-ASIS line. The Anterior Pelvic Plane alsocontains Point 3 to define the plane. The Adjusted Plane utilizes thedirection of gravity to define the plane. In some embodiments, theAnterior Pelvic Plane and the Adjusted Plane are coaxial about theinter-ASIS line as shown in FIGS. 28B and 28B-1. The Adjusted Plane is arotation of the Anterior Pelvic Plane about the inter-ASIS line. TheAdjusted Plane and the Anterior Pelvic Plane can form an angle alpha asshown in FIGS. 28B and 28B-1. The angle alpha can be a measurement ofpelvic tilt. The angle alpha can measure the difference to horizontalfrom the Anterior Pelvic Plane. The angle alpha can adjust the AnteriorPelvic Plane such that the cup angles more closely match those shown inpost-operative x-rays. In some embodiments, the Adjusted Plane adjustsfor tilt. In some embodiments, the Adjusted Plane adjusts for tilt ofthe pubis relative to the inter-ASIS line.

The Adjusted Plane has clinical value. The pre-operative andpost-operative x-rays produce two-dimensional images on a horizontalplane. The image receptor is positioned horizontally relative to thepatient in the supine position. The image receptor captures the remnantbeam as the beam exits the body of the patient. The anatomy of thepatient is projected onto the horizontal plane of the image receptor.For pelvis x-rays, the routine projection is an anterior-posteriorprojection. The navigate angles can be correlated to the view of thepost-operative x-ray via the Adjusted Plane. The Adjusted Plane mayprovide a horizontal reference plane that approximates the horizontalreference plane of imaging techniques. There is a clinical benefit inproviding users with navigated cup angles during a procedure that willreflect those measured on post-operative x-rays. The navigated cupangles based on the Adjusted Plane can be provided in addition, or as asubstitute to those based on the Anterior Pelvic Plane. The navigatedcup angles based on the Adjusted Plane can be provided in addition, oras a substitute to those based on the table plane.

The adjustment from the Anterior Pelvic Plane to the Adjusted Plane canprovide the user with cup angles that correlate to clinically expectedcup angles. The adjustment from the Anterior Pelvic Plane to theAdjusted Plane can provide the user with cup angles that correlate towhat they expect to see during surgery (e.g., a comparison between theimage of the cup and the output of the system 600). The adjustment fromthe Anterior Pelvic Plane to the Adjusted Plane can provide the userwith cup angles that correlate to what they expect to see onpost-operative images (e.g., a comparison between the output of thesystem 600 and post-operative images). The user, such as a surgeon,correlates the output of the system 600 with numbers that correlate toclinical experience, e.g., calibrated to what they expect to see inpost-operative images. The post-operative images can be 6 weekpost-operative supine films. The post-operative images are taken from ahorizontal cross-section of the patient's body. The Adjusted Plane maybe more similar to the plane of the post-operative images.

Before navigation systems, such as system 600, surgeons did not takemeasurements intra-operatively. Rather, surgeons typically looked at thecup placement during a procedure and determined whether current cupplacement looked like previous cup placements. The surgeon wouldvisually confirm cup placements during surgery and past experience inviewing post-operative images. The user would determine if the currentcup placement was likely to correlate to the correct abduction andanteversion angles post-operatively. The surgeon would look at the cupplacement and determine that the placement looks like 40 degrees×15degrees based on their experience looking at post-operative images. Thesurgeon's confidence in the procedure would be based on theircorrelation of cup placement and post-operative images.

For the system 600, the user is provided with an output that assists auser to navigate to proper cup placement. The output can be abductionand anteversion angles displayed on the surgical orientation device 172.The user can navigate to the desired abduction and anteversion angles bymoving components of the system 600, such as the impactor. When the userplaces the cup at the desired abduction and anteversion angles, the userwants to see the same or similar angle on post-operative images. Theuser's confidence in the navigation of the system 600 increases if theabduction and anteversion angles produced by the system 600 match thepost-operative images.

The Adjusted Plane can be an improvement over a landmark-only referenceplane, such as the Anterior Pelvic Plane, for some patients. In someembodiments, the Anterior Pelvic Plane may differ from the horizontalreference plane of imaging techniques due to patient specific factors.For instance, pelvic tilt may orient the Anterior Pelvic Plane at anangle from the horizontal reference plane of imaging techniques. Forinstance, the patient's high body mass index may impact the ability tocontact anatomical landmarks. For instance, the anatomical features ofthe reference points may not be visible and/or palpable while thepatient is in a supine position. For instance, the ipsilateral ASIS, thecontralateral ASIS, and/or the pubic symphysis may not be visible and/orpalpable. The patient specific factors can results in differencesbetween navigated cup angles from the Anterior Pelvic Plane and anglesmeasured post-operatively. In some methods of use, with some patients,the Anterior Pelvic Plane may not provide abduction and anteversionangles that match post-operative images.

The Adjusted Plane can be an improvement over a table plane-onlyreference frame for procedures. In some embodiments, the table plane maydiffer from the horizontal reference plane of imaging techniques. Theuser may introduce errors in the table plane by improper placement ofthe probe 678. In some methods of use, with some patients, the tableplane may not provide abduction and anteversion angles that matchpost-operative images.

In some methods of use, two or more reference planes can be provided,e.g., any combination of the Adjusted Plane, the table plane, thehorizontal plane and the Anterior Pelvic Plane. Any of the foregoingcombinations of the reference planes provides redundancy that ensuresthat the angle information provided to the user is accurate and reliablesuch that the procedures performed will be better contained within anacetabular cup “safe zone”.

Systems and methods described herein can improve prosthetic hip jointplacement using navigation in combination of pre-operative imaging andlandmark referencing. These hip procedures generally guide a prosthetichip to an orientation within the acetabulum that minimizes the chance ofdislocation due to impingement of the femoral neck on the cup or onbones around the acetabulum or other reasons related to suboptimalorientation of the prosthetic. Various techniques leverage populationaverages of proper placement while others are amenable to patientspecific refinements.

3. Pelvis Tracking

FIG. 29 shows a screen display for a hip method generated by oneembodiment of the interactive user interface of the surgical orientationdevice 172. Once the orientation sensing device 204 is attached to theimpactor 300A or any other impactor coupled to the universal impactoradapter 350, 352, the surgical orientation device 172 can displayradiographic abduction and anteversion angles of impactor relative to areference plane. The reference plane can be any plane including afrontal pelvic plane, the Anterior Pelvic Plane, the table plane, theAdjusted Plane, etc. The surgical orientation device 172 can displayabduction and anteversion angles relative to two or more planes. In theillustrated embodiment, the surgical orientation device 172 can displayradiographic abduction and anteversion angles relative to the AnteriorPelvic Plane. The surgical orientation device 172 displays “Pelvis”angles relative to the Anterior Pelvic Plane. The Anterior Pelvic Planeis based on inputs from the anatomic landmarks. In the illustratedembodiment, the surgical orientation device 172 can display radiographicabduction and anteversion angles relative to the Adjusted Plane. Thesurgical orientation device 172 displays “Adjusted” angles relative tothe Adjusted Plane. The Adjusted Plane is a reference plane where theAnterior Pelvic Plane is rotated about the inter-ASIS axis until itssuperior-inferior axis is parallel to the level table. This effectivelyadjusts for pelvic tilt. The “Adjusted” angles may correlate withpost-operative x-rays which use a horizontal plane.

The surgical orientation device 172 can display additional informationfor the user. For instance, the surgical orientation device 172 candisplay information related to the position and orientation of thepelvis. As described herein, the surgical orientation device 172 can becoupled to the pelvis such that the surgical orientation device 172 canmeasure changes in the pelvis. The surgical orientation device 172 caninclude one or more inertial sensors that can track the position of thepelvis during the procedure. The surgical orientation device 172 candisplay the change in positioning of the pelvis in real time. Thesurgical orientation device 172 can provide an indicia if the positionof the pelvis has changed beyond a threshold, for instance by a visualor audial cue.

The surgical orientation device 172 can track pelvic tilt. The tilt ofthe pelvis can be displayed dynamically on the surgical orientationdevice 172. FIGS. 30A-30C illustrate the tilt of the pelvis. At thestart of the procedure, the pelvis may be ideally positioned. However,the pelvis can shift through the rigors of the procedure. The surgicalorientation device 172 can provide information about where the pelvis isrelative to the rest of the body. The surgical orientation device 172can indicate pelvic tilt from a neutral position. The surgicalorientation device 172 can indicate a posterior tilt or an anteriortilt. The surgical orientation device 172 can track the pelvisthroughout the surgical procedure.

The surgical orientation device 172 can track pelvic rotation. Therotation of the pelvis can be displayed dynamically on the surgicalorientation device 172. FIGS. 31A-31C illustrate the rotation of thepelvis. The surgical orientation device 172 can indicate a pelvicrotation. The surgical orientation device 172 can include one or moresensors to provide an output. The surgical orientation device 172 cantrack the pelvis at the pelvis moves during the procedure. The surgicalorientation device 172 can graphically display when the pelvis islocated at neutral rotation. For instance, the neutral rotation can berecorded by the surgical orientation device 172 at the beginning of aprocedure when the pelvis is ideally placed.

Referring back to FIG. 29, the screen display of the surgicalorientation device 172 can indicate pelvic tilt. In the illustratedembodiment, pelvic tilt is shown as a measurement of an angle. Thescreen display of the surgical orientation device 172 can indicatepelvic rotation. In the illustrated embodiment, pelvic tilt is shown asa measurement of an angle.

The surgical orientation device 172 can include indicia such as a targetor bullseye to indicate when the pelvic tilt and pelvic rotation areneutral. In the illustrated embodiment, pelvic tilt can be along theY-axis or vertical axis of the bullseye. In the illustrated embodiment,pelvic rotation can be along the X-axis or horizontal axis of thebullseye. The surgical orientation device 172 can include indicia suchas a dot to indicate the degree of pelvic tilt and rotation. The indiciacan move in real-time. As the degree of pelvic tilt increases, theindicia can move further away from the origin or center of the bullseye.As the degree of pelvic tilt decrease, the indicia can move closer tothe origin or center of the bullseye. As the degree of pelvic rotationincreases, the indicia can move further away from the origin or centerof the bullseye. As the degree of pelvic rotation decrease, the indiciacan move closer to the origin or center of the bullseye. The indicia canassist the user in understanding the alignment of the pelvis. Theindicia can assist the user in positioning the pelvis. For instance, theuser can reposition the pelvis during surgery to a neutral position,such as a position having neutral tilt and/or neutral rotation.

Referring back to FIG. 28C, the Adjusted Plane can be provided bytransforming, e.g., by rotating the Anterior Pelvic Plane to correct forpelvic tilt. The Adjusted Plane can rotate the Anterior Pelvic Planeabout the inter-ASIS line to correct for anterior tilt or posteriortilt. The transformation between the Anterior Pelvic Plane and theAdjusted Plane accounts for tilt of the patient's pelvis. Thetransformation between the Anterior Pelvic Plane and the Adjusted Planeaccounts for pelvic tilt due to the location of the pubic symphysis. TheAdjusted Plane rotates a location corresponding to the pubic symphysisin the Anterior Pelvic Plane from the position in which the pubicsymphysis was probed to a horizontal location.

Referring to FIGS. 31A-31C, pelvic rotation corresponds to the relativelocation of the ipsilateral ASIS and the contralateral ASIS. Regardlessof pelvic rotation, the inter-ASIS line connects the ipsilateral ASISand the contralateral ASIS. The Adjusted Plane and the Anterior PelvicPlane both contain the inter-ASIS line.

Although these inventions have been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that this application extends beyond the specificallydisclosed embodiments to other alternative embodiments and/or uses ofthe invention and obvious modifications and equivalents thereof. Inaddition, while a number of variations of the inventions have been shownand described in detail, other modifications, which are within the scopeof the inventions, will be readily apparent to those of skill in the artbased upon this disclosure. It is also contemplated that variouscombinations or sub-combinations of the specific features and aspects ofthe embodiments may be made and still fall within the scope of theapplication. For example, the application contemplates the connectionhub alone or in combination with any of the other modules could comprisea separate aspect. Or, any one or a combination of the modules could bedirectly connected to an umbrella hub or overhead support to formanother separate aspect. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the disclosed embodiments. Thus, it is intended that the scopeof the present invention herein disclosed should not be limited by theparticular disclosed embodiments described above, but should bedetermined only by a fair reading of the claims that follow.

Similarly, this method of disclosure, is not to be interpreted asreflecting an intention that any claim require more features than areexpressly recited in that claim. Rather, as the following claimsreflect, inventive aspects lie in a combination of fewer than allfeatures of any single foregoing disclosed embodiment. Thus, the claimsfollowing the Detailed Description are hereby expressly incorporatedinto this Detailed Description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. A method of positioning a medical prosthesis comprising: establishing a vertical plane with a measuring device; projecting a pattern of light onto the leg of a patient; recording the incidence of light on the leg of a patient; replacing the joint by inserting a cup, wherein one or more angles of the cup are measured relative to the vertical plane; projecting the pattern light onto the leg of the patient after replacing the joint; repositioning the leg to align the recording of the incidence of light with the pattern of light.
 2. The method of claim 1, further comprising determining a change in leg length in the vertical plane.
 3. The method of claim 1, further comprising determining a change in joint offset in a plane perpendicular to the vertical plane.
 4. The method of claim 1, further comprising establishing a horizontal plane with a measuring device, wherein the vertical plane and the horizontal plane define a reference frame.
 5. The method of claim 4, further comprising recording a point in the reference frame.
 6. The method of claim 4, further comprising recording a point pre-operatively in the reference frame.
 7. The method of claim 4, further comprising recording a point post-operatively in the reference frame.
 8. The method of claim 1, further comprising recording a position of a probe when contacting a point pre-dislocation.
 9. The method of claim 1, further comprising recording a position of a probe when contacting a point post-instrumentation.
 10. The method of claim 1, further comprising determining a change in leg length.
 11. The method of claim 1, further comprising determining a change in joint offset.
 12. A method of positioning a medical prosthesis comprising: coupling a measuring device and probe to a patient; positioning the probe to contact a first point; recording the position of the probe when the probe is contacting the first point; positioning the probe to contact a second point; recording the position of the probe when the probe is contacting the second point; positioning the probe to contact a third point; recording the position of the probe when the probe is contacting the third point wherein the first point, the second point, and the third point define a plane; and establishing an adjusted plane by rotating the plane by the direction of gravity.
 13. The method of claim 12, further comprising positioning the probe horizontally to measure the direction of gravity.
 14. The method of claim 12, further comprising determining cup angles relative to the reference plane.
 15. The method of claim 12, further comprising positioning a medical prosthesis at an angle relative to the adjusted plane.
 16. The method of claim 12, wherein the first point and the second point define the inter-ASIS line.
 17. The method of claim 12, wherein the first point, the second point, and the third point define the anterior pelvic plane.
 18. The method of claim 12, wherein the first point is the ipsilateral ASIS.
 19. The method of claim 12, wherein the second point is the contralateral ASIS.
 20. The method of claim 12, wherein the third point is the anterior surface of the pubic symphysis. 